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IMO D1 and D2 Standards Ballast Deballast Survey

Ballasting and Deballasting is the term used to stabilize ships in the water, especially when ship is discharged from all heavy load, it becomes light in weight hence unbalanced to float smoothly on the surface. So ballasting is taking water into the tanks of the ship to meet the standard load for balancing and same manner when the ship needs loading, deballasting is required or may be this process required in certain circumstances as well when the ship sails.

As per International Maritime Organization (IMO) there are two standards for ballast water management:

D1 Standard – Ballast Water Exchange (BWE)

First standard is the D1 standard which refers to Ballast Water Exchange (BWE). For BWE, efficiency of at least 95% volumetric exchange of ballast water is required. Efficiency is considered as 95% standard when the ship uses to have pumping-through method and where it pumps three times. This entire operation has to be done while ship conducts 200 nautical miles operations from the shore/land, and the water should meet the standard of min 200 meters deep. It is better to go as far as from the land to undertake BWE operation however, minimum 50 nautical miles could also be considered however, under no conditions water depth should not be less than 200 meters. One more thing to remember is, to contact the port state administrators to confirm Ballast Water Exchange requirements within local waters.

D2 Standard – Ballast Water Performance

D2 standard refers to performance of the ballast water and this is all about chemistry and the laboratory testing where we need to get report for D2- Ballast Water Performance Testing from accredited lab. Purpose of D2 standard is to stipulate the level of acceptance of organism that could be found in the discharge ballast water.

  • The viable organisms fewer than 10 greater than or equal to 50 micrometers in minimum dimension per cubic meter;
  • The viable organisms fewer than 10 less than 50 micrometers in minimum dimension and greater than or equal to ten micrometers in minimum dimension per milliliter.

Additionally, a ballast water discharge of indicator microbes, as a health standard, shall not exceed the following specified concentrations:

  • Toxicogenic Vibrio cholerae (O1 and O139) with less than one colony-forming unit (cfu) per 100 milliliters or less than 1 cfu per 1 gram (wet weight) zooplankton samples;
  • Escherichia coli less than 250 cfu per 100 milliliters;
  • Intestinal Enterococci less than 100 cfu per 100 milliliters

If you require our services, please visit our page Ballasting and Deballasting Inspection Services or you require ballast water analysis, please visit our page Ballast Water Testing for all the specifications.


Vessel Surface Coating Condition Survey

Adequate surface protection is fundamental in coatings work. The surface finish or coating should have a pleasant appearance and be able to protect the structure against deterioration from its more or less corrosive surroundings and to some degree from mechanical loads and impacts.

The psychologically positive effect of an aesthetically successful coating should not be underestimated, even in ships’ ballast tanks. This is clearly demonstrated by the lengthy discussions about the IMO/SOLAS recommendation of using light-colored coating, 5–6 which basically was introduced to facilitate inspections.

The “market” concerned with protective coatings for ships includes not only ship owners and shipyards but also maritime authorities, ship brokers, the coating industry, the ships’ crew, and really the general public.

In simple terms, shipyards have a fundamental interest in building ships quickly and effectively. The market generally wants ships to be in good shape, nice looking, safe, and economical in operation.

Surface protection, including steel preparation and application of coating materials, adds considerable cost to a ship, so an optimal coating quality at an acceptable cost must be sought.



ship-surface-coating-survey-2 ship-surface-coating-survey-3

Critical areas for corrosion on single hull tankers.


Critical areas for corrosion on double hull tankers.


Typical areas under consideration in the after peak and fore peak ballast tank on a tanker and bulk carrier.



Special Thanks to Capt. Harry González




Draft Survey Guide

How to Conduct Bunker Survey
What is Bunker Survey? The survey is carried out to measure and ascertain the quantity of Bunker onboard at the specific time. This survey is produced the report that states the amount of bunker, usually Fuel Oil (FO) and Diesel Oil (DO), and sometimes Lubricating Oil (LO) is included.


In this post limits to how to conduct the Bunker Survey on the ship tanks only.

Survey Tools required for Bunker Surveyor
  • Notes Book,
  • Sounding Tape,
  • Thermometer,
  • Density Meter for Oil (),
  • Oil and Water Paste,
  • Petroleum ASTM Table 54B (for Product Oil) and Table 56,
  • Flashlight,
  • Sampling Can,
  • Bottle or Can for Sampling (if required taken samples).
 Steps for Conducting Bunker Survey

Identify and records the number and Depth of Tank, Reference Height, and Measuring Method recommended to use (Ullage or Sounding) for each Oil Tank. Sounding is determined the level of liquid tank from the bottom of the tank to the liquid surface (typically applied for light liquid).

Ullage means to determine the level of liquid of tank by measured the empty space from top of the Tank (the mouth of Sounding Pipe) to the liquid surface (typically applied for heavy liquid). The both methods will point to the same result.

Record the Last Bunker Report, Time and Place of last Bunker supplied, includes the Oil density.

Records the quantity of bunker onboard when the ship arrives at Port (arrival Condition) as per Engine Log Book.

Checking the accuracy of the Sounding Tape, it is recommended to use your own Sounding Tape. In case we used Ship’s Sounding Tape, please checking the tape.

Sounding each Oil Tank and records the level of Oil on the tank. Attached the sounding Tape with Oil Paste to make easy and clear to show of oil level (recommended for Light Oil).

Check the Ship’s Draft Marks to get the Ship Trim for Trim correction, and check the ship Inclination or Listing for List Correction, that is required to calculate the Tank Quantity Table.

Taken Oil sample, check temperature and oil density, for the accessible tank only. The Service and Settling Tanks are not accessible due to the oil on that tanks were in heating condition at the high temperature. We could records the tank gauging for determining the quantity, the temperature at the thermometer available on each tank, and the Oil Density from the Engine Log Book. If you could not taken the oil sample for checking density, it is recommended to calculate the Density Commingle, by means the Combine Density between two Oils (Old and New Oils) that has mixed on one tanks which they have different in Density. Where it is approaching the actual oil density, the pattern is {(Old Oil Quantity x Oil Density / Total Oil on Tank) + (New Oil Quantity x Oil Density / Total Oil on Tank)}.

Calculations, this stage will involved the Sounding level of each tank, Ship’s Trim and List, Tank Quantity Table (provided by Ship’s Chief Engineer), Oil Density and Temperature, ASTM Table 54B to ascertain the Volume Correction Factor (VCF – to convert from Cubic Meter to Kiloliter) and ASTM Table 54B for Weight Correction Factor (WCF – to convert from Kiloliter to Metric Ton). 

Example to calculate Density Commingle: FO Tank No. 1 C, total oil on tank 400 Cu.M, Old Oil 200 Cu.M with density 0.9870, and New Oil 200 Cu.M with density 0.9720. Density Commingle = {(200 x 0.9870 / 400) + (200 x 0.9720 / 400)} = 0.4935 + 0.4860 = 0.9795.

Issued the Tank Sounding and Bunker Report.

Draft Survey: Procedures and Calculation



The Draft Survey procedures and calculation ascertained as the following series :

  1. Reading the draftmark of the ship, which consist of six (6) points of draftmarks, i.e.; Fore, Midship, and After at both sides of the ship,
  2. Sampling and testing the sea water or dock water density at the place where the vessel floats,
  3. Determining of deductible weights by measuring and sounding of ballast tanks, fuel oil, fresh water that existing onboard at the time of survey,
  4. Using Hydrostatic Table provided onboard to calculation.
Reading the Draftmark of the ship
Commonly, all ship are designed with draftmark for working with Draft Survey to determined their actual weight. The draftmark could be find at six (6) points on the below places:
  • Forward Port Side (FP),
  • Forward Starboard Side (FS),
  • Midship Port Side (MP),
  • Midship Starboard Side (MS),
  • Aftward Port Side (AP),
  • Aftward Starboard Side (AS),
View the Draftmark:
Use the small boat to go around the ship and get as near as possible to the draft mark for best viewing. The surveyor should be read all above marks clearly, because reading the draftmark is the first and most essential process. I am not saying that other processses is not essensial, but this process is hard to do and involves many rules of conduct to gain the correctness and accuracy of Draft Survey itself (I will post it later). The draftmark read is recorded on the surveyor notebook, do not try to remember it or write down in your palm hand. Its useless and un-professional.
Sampling and testing the sea water or dock water density 
After reading the draftmark, directly engage with the sampling of sea water or river water around the ship’s dock.  Why? Because the ship draft will not be the same at different water densities (at the lower density means the ship more sink and at the higher density means the ship more float).  Where as the water density is subject to changes which follow with water tide that carrying different water salinity and temperature on to the ship dock. The sea water density is indeed at density 1.025 and the fresh water at density 1.000. To determine the density of water, we need the instrument named Hydrometer or Density Meter. Inserted the Hygrometer on to the water sample on the Sampling Can or Tube, then we could check the scale pointed on the surface of the sampling water. Records the water dock density as survey data.
Determining of deductible weights by measuring and sounding
Deductible Weight could measure by sounding  the tanks which used the Sounding Tape or gauging the tank level by visual inspection. Any deductible weight such as Ballast Water, Fresh Water, Fuel and Diesel Oil, and Bilges is notify to check. Records all in the survey book includes with the density for Ballast and Bilges, and for Oil complete it with density and temperature . The Fresh Water was at density 1.000.
View the Sounding Pipe:
Using Hydrostatic Table provided onboard to begin calculation, 
I think all necessary data was completed, so we could do calculation. The calculation is uses Displacement Table or usually called Hydrostatic Table. This table is included all data that we need to complete the calculation.
  • Raw Draft Calculation; Fore Mean or Fm = (FP+FS)/2, Mid Mean or Mm = (MP+MS)/2, and Fore Mean or Am = (AP+AS)/2. while Apparent Trim  or AT = Am – Fm. the Apparent Trim is the Trim that visually find.
  • Draftmark posision and correction to perpendicular. As the ship draftmark is not placed at the perpendicular, the Fore and After draft should be corrected with distance from the draftmark to perpendicular. The correction rules is: if the Trim by Stern, the Fore correction should be minus and After correction plus, and if the Trim by Head (stem), the Fore correction should be plus and After correction minus. The Midship correction is parallel with the fore correction with the same pattern. Some Hydrostatic table provided with these correction result. But if not the reference pattern is  for Fore Correction or Fc = (Fd x AT) : LBM and After Correction or Ac = (Ad x AT) / LBM. Where Fd = Fore distance to perpendicular, Ad = After distance to perpendicular, and LBM = Length Between Mark or Length between Fore and After draftmarks  or LBM = LBP – (Fd + Ad).
  • True Draft Calculation / Draft Corrected; Fore draft corrected or Fcd = Fm + Fc, Mid draft corrected or Mcd = Mm + Mc, and After draft corrected or Acd = Am + Ac.
  • True Trim or TT : Actual  Ship Trim after draft corrected or  TT = Acd – Fcd.
  • Fore and After Mean Draft or FAm = (Fcd + Acd)/2, Mean of Mean Draft or MM = (FAm + Mcd)/2, and Mean of Mean of Mean Draft  or MMM or Quarter Mean = (MM + Mcd)/2.
  • The above calculation is similar with : MMM = {(Fcd x 1) + (Acd x 1) + (Mcd x 6)}/8.
  • Coresponding to the MMM or Quarter Mean result, the surveyor could check the value of needed parameters on Hysdrostatic table like; Displacement, TPC, LCF, and MTC. Records them accurately.
  • Get the Displacement or Disp.
  • First Trim Correction or FTc = (TT x LCF x TPC x 100) / LBP. Could be plus or minus depend on LCF.
  • Second Trim Correction STc = (TT x TT x MTC x 50) / LBP. The result always plus (+).
  • Displacement corrected by Trim or DispT = D – (FTc + STc).
  • Density Correction or Denc = DispT x {(Aden – 1.025) / 1.025}. where the Aden is Actual Density that surveyor has taken sampling and testing previously. The density correction commonly in minus (-), due to the Actual Density is usually lower than 1.025 (fresh sea water). In case of at some port where the water salinity is high, the density correction could be plus (+).
  • And we have got the Displacement corrected by Density or DispDenc = DispT + Denc. (after corrected by density we will get the actual ship weight as per shown by Draft Survey).
  • Deductible Calculation. The same as draft, the deductible also need to corresponding to the table that named Tank Table / Tank Capacity Table. Refer to the sounding records that done before, the surveyor could be calculate the total deductbile existing onboard. Total Deductible or Deduct =  Ballast Water + Fresh Water + Bilges + Fuel Oil + Diesel Oil,  this total should be minus to the Displacement corected by Density.
  • The Net Displacement or NDisp = DispDenc – Deduct.
  • The Net Displacement is the actual ship weight after minus with deductible weight. For Unloading, to estimate the quantity of cargo onboard, the Net displacement should be minus withLight Ship and Constant.


Special Thanks to Capt. Harry González



Initial Hull Survey and Annual Hull Survey



Initial Hull surveys

The initial survey, as required by the relevant regulations, should be held before the ship is put in service and the appropriate certificate is issued for the first time.

The initial survey before the ship is put into service should include a complete inspection, with tests when necessary, of the structure, machinery and equipment to ensure that the requirements relevant to the particular certificate are complied with and that the structure, machinery and equipment are fit for the service for which the ship is intended.

The initial survey should consist of:
an examination of the plans, diagrams, specifications, calculations and other technical documentation to verify that the structure, machinery and equipment comply with the requirements relevant to the particular certificate;
an inspection of the structure, machinery and equipment to ensure that the materials, scantlings, construction and arrangements, as appropriate, are in accordance with the approved plans, diagrams, specifications, calculations and other technical documentation and that the workmanship and installation are in all respects satisfactory;
a check that all the certificates, record books, operating manuals and other instructions and documentation specified in the requirements relevant to the particular certificate have been placed on board the ship.

Examination of plans and designs
An application for an initial survey should be accompanied by plans and designs as required by Administration or Class Society, as appropriate, together with:
the particulars of the ship;
any exemptions sought;
any special conditions.


Annual Survey of Hull


The annual survey, as required by the relevant regulations and as shown diagrammatically in the harmonized system of survey and certification, should be held within three months before or after each anniversary date of the certificate.


An annual survey should enable the Administration to verify that the condition of the ship, its machinery and equipment is being maintained in accordance with the relevant requirements.

In general, the scope of the annual survey should be as follows:

a. it should consist of a certificate examination, a visual examination of a sufficient extent of the ship and its equipment, and certain tests to confirm that their condition is being properly maintained;

b. it should also include a visual examination to confirm that no unapproved modifications have been made to the ship and its equipment;

c. the content of each annual survey is given in the respective guidelines. The thoroughness and stringency of the survey should depend upon the condition of the ship and its equipment;

d. should any doubt arise as to the maintenance of the condition of the ship or its equipment, further examination and testing should be conducted as considered necessary.

Where an annual survey has not been carried out within the due dates, reference should be made to re-validation of certificates.


Special Thanks to Capt. Harry González



Hull Survey Guide with Methods

Hull survey methods, are means and procedures to detect failure and damage at an early stage to avoid premature breakdown.

Hull survey methods are therefore not only comprehensive means of detecting deficiencies or monitoring structural condition, but also of defining schemes for inspection between the last overhaul and before the occurrence of failure.

Means of detection of defects and condition monitoring are inter alia:

  • Visual inspections
  • Non-destructive testing (NDT) and calibrating
  • Examination of tightness, function and centre of gravity
  • Measurements of thickness, vibration

Schemes of inspection are periodical survey requirements which by virtue of design and operational experience are envisaged to discover deficiencies completely and early enough before they may lead to breakdown.



1.1 Visual Inspection
A major part of hull surveying work is carried out using visual skills to perform the examinations and to arrive at an opinion on the state of a vessel’s condition.

Such visual examinations can be carried out as:

  • Over-all inspections, a general sighting of a vessel’s hull condition, followed by
  • Close-up examinations at
  1. locations where discontinuities, ruptures or deformations have been found and
  2. certain hull structures as stipulated by rules and/or requirements, for instance in way of cargo area of oil tanks.
  • Examination of areas of suspected crack and corrosion concentration.

The methods of visual inspection procedures may be applied as follows:
1.1.1 Visual over-all inspection
Examination of external hull body

Visual attention is to be focused on the vessel’s shapes, lines and curves for the detection of

  • unusual deformation,
  • misalignment of structures along bottom plating, side shells, bilge keels, decks.

As a result, permanent deformations of misshaped sections can be caused by:

  •  hogging
  • sagging
  • bagging
  • local deflections from the original structure.

For measuring purposes, a wire or a piano line may be stretched out from forward to aft and gauging derived from such a zero basis.
Inside inspections in holds, tanks, hull parts
Similar visual examinations can be carried out inside of compartments:
Attention should be concentrated on the lack of straightness of structures, along side lines from forward to aft and from port to starboard, with regard to:

  • stringers and longitudinal frames,
  • walls, longitudinal bulkheads and corrugations,
  • platforms, transverse members and bulkheads,
  • frames, brackets, deck beams,
  • floors and attached stiffeners.

Lines and/or structures showing misalignment, deflection, buckling or other discontinuities, are an indication of existing defects requiring close-up inspection.
Docking inspections
When a vessel is dry-docked, attention has to be focused on:

  • discovery of deformations and/or discontinuities along keel plates, bottom, and side plates, bilge keels, and attachments,
  • checks for leakages from inside to outside, if the ballast
  • tanks have overflow prior to this inspection,
  • removal of the drain plug at the rudder blade. If water leaks out this is an indication that the blade has suffered water ingress (which may otherwise have remained hidden);
  • measurement of rudder bearing clearances by feelers can also be considered a visual approach to assess wear-down. Ditto calibration of anchor chain links by caliper slide,
  • condition of rudder flange; bolts or nut(s) must be absolutely tight;
  • condition of welding at seams and butts and in way of outlet openings.

1.1.2 Close-up examination

If indentations and/or deformations have been located, visual close-up examinations are necessary.

The area under scrutiny should be accessible for visual inspection within bodily reach.
Such inspections should be carried out with floodlight etc. A good torch and a test hammer should always be available, as well as a scraper to remove rust scale and debris to reveal the bare material underneath.

In case of deformation
Deformations that may have been produced as a result of external or internal forces should be carefully analyzed.
Without apparent extra loads along shell, deck, or bottom, likelihood of the following should be checked:

  • internal movement of cargo, liquids etc.
  • excessive flexibility of the structure.
  • local stress concentrations (point loads excessive).

Further examinations for fractures and incipient cracks may be necessary.

Also other identical locations should be examined to see whether similar defects exist or are developing.

In case of cracks

  • location of crack,
  • configuration of the structure/element,
  • starting point of the crack,
  • length and direction,
  • depth and width of the crack,
  • possible cause(s):

=        defective welding of assembled parts,

=        discontinuation of joints,

=        compression or tension of adjoining parts,

=        twisting motion,

=        reduced thickness,

=        type of corrosion, etc.

should be checked not only in the respective area, but also in other identical locations, especially at the opposite side.

1.1.3 Areas of concern for cracks and corrosion

Locations of stress concentration and crack raisers

On deck:

–        Corners of hatches on weather decks,

–        corners at deck connections to deckhouses and superstructures,

–        deck plating between cargo hatches, especially where plate thickness changes,

–        at bulwark stay deck connections.

Under deck:

–        Cutouts at webframes where longitudinal pass,

–        cutouts at bulkheads where longitudinal passages are closed,

–        tips of bracing plates (knee brackets) at bulkhead connections,

–        areas where longitudinal members meet vertical structures.

In machinery spaces:

As above in under-deck locations and especially

–        at areas of induced vibration (around oscillating machinery),

–        underneath of engine seats/along foundations,

–        at thrust bearing seats.

Locations where accelerated corrosion is likely

–        Generally where the coating is inadequate, defective, or poorly maintained,

–        corners and dead ends where water is restricted from draining or flowing away (i.e. bottom connection at aft bulkheads),

–        inside of scupper pipes, especially at the elbows where the scuppers are led into the shell,

–        at bulwark and coamings stays in way of deck connection,

–        along deck connections with coamings of hatches, venti1ation trunks, air pipes, etc.,

–        on top or underneath of air and ventilation pipes/trunks, especially where galvanized parts are fitted to steel.

At hatch covers:

–        between panel joints and especially along rain gutters, sealing bars, and rubber channels,

–        along underside of panel side walls in contact to hatch coaming,

–        in pockets of lashing points, etc.


At hatch coamings:

–        along sealing bar,

–        along roller tracks.

Under deck (cargo holds/tanks):

–        along aft transverse bulkheads in way of deck/tank deck connection where water or cargo rests are likely to stay,

–        inside of bilge trunk,

–        base of sounding pipes (where doublers should be fitted),

–        base of suction pipe bell mouths,

–        in way of pipe clamps and fittings,

–        at the undersides of pipelines where condensate is dripping,

–        in ballast tanks along the area of air between filling level and tank top,

–        at pipes, especially along their outer rear side, fittings and outer undersides.

1.2 Non-destructive Testing Methods

The detection of cracks by visual methods is rather limited. Additionally internal welding seam imperfections or flaws in material parts cannot be discovered without suitable means of examination and instrumentation. To discover these suitable means of non-destructive testing (N.D.T.) are used, such as:

–        Dye checks with liquid penetrants

–        Magnetic particle checks

–        Radiographic checks, or

–        Ultrasonic measurements.

1.2.1 Liquid penetrant methods (dye checks)

One type of test uses a low viscosity liquid, containing a fluorescent dye. The area to be tested is sprayed or soaked to allow for penetration by capillary action, and after a time lapse is wiped dry. When viewed under ultra violet light, any faults will be shown by the glow of the penetrant in them.


Another test uses a penetrant containing a powerful dye. This is sprayed on the suspect area with an aerosol. After allowing time for penetration, the area is wiped clean and covered with a liquid which dries to leave chalky sediment (developer). The penetrant stains the developer along the line of the crack.

These methods are based on old chalk and paraffin tests but the penetrant can have a hydrocarbon or alcohol base. Some are emulsifiable for removal by water spray, others can be cleaned off with solvents to reduce possible fire risk.

1.2.2 Magnetic crack detection

This type of test is suitable only for materials which can be magnetized (cannot be used for austenitic steels or non-ferrous metals). After the test the component is normally de-magnetized.


A magnetic field is produced in the component by means of an electric current or permanent magnet and magnetic particles are spread on the surface. Cracks are revealed by a line of magnetic particles.

The powder used may be black iron oxide held in suspension in thin oil. It is poured onto the surface, the surplus being collected in a tray beneath. Colored magnetic inks in aerosols are also available and the dry method makes use of powder only and this is dusted on the surface. Powder tends to collect at a crack in the same way as iron filings will stick to the junction of two bar magnets, placed to end with opposite poles together.

1.2.3 Radiographic inspection

X-rays and gamma rays are used for inspection of welds, castings, forgings etc. Faults in the metal affect the intensity of rays passing -through the material. Film exposed by the rays gives a shadow photograph when developed.

There is a requirement for radiographic examination of many welds, particularly those in pressure vessels.

Defects such as porosity, slag inclusions, lack of fusion, poor penetration, cracks and undercutting are shown on the film.

Films of radiographic examination provide a permanent record of quality of welds etc. and must be identified by serial numbers or other location marks. Image quality indicators are placed on or adjacent to welds.

Radiographs are viewed by a radiologist on a uniformly illuminated diffusing screen. Training is necessary for the interpretation of film, both with regards to the faults in the part being examined and misleading marks that sometimes appear on film.

A skilled radiographer is required for the obtaining of photographs.

Exposure times for gamma rays vary with the type of material, its thickness and the intensity of the rays. X-ray machine voltage and exposure time are also varied to suit the material and its thickness. Distances between ray source, faults and film are important for image definition.

Rays are harmful either in a large dose or a series of small ones where the effect is cumulative.

Monitoring against overdose is necessary with film badges, medical examination and blood counts.

Direct exposure is avoided by the use of protective barriers but there is a danger that objects in the ray path will scatter radiation.

1.2.4 Ultrasonic testing

Internal flaw detection by ultrasonic means is in principle similar to radar. The probe emits high frequency sound waves which are reflected back by any flaws in the object. Reflect ions are also received back from the opposite surface. The probe is connected to a cathode ray oscilloscope which shows the results in a simple way.

A single probe can be used, which combines both transmitting and receiving functions. Alternatively separate devices for transmitting and receiving the sound signals are available.

Any flaw in the material being inspected will also produce a peak.

The following details of “US Testing of Hull Butt welds” from BUREAU VERITAS Weld testing principle:

Transverse waves are emitted from an angle probe moved on the plate surface on either side of the weld.

The probe displacement should be sufficient for scanning the whole weld over a single or a double traverse, as shown on Figure 8.

As far as possible, and taking into account the plate thickness, scan from both sides of the weld, especially for detecting longitudinal defects.

–        The scanning operation depends on the type of plate edge preparation before welding and on the configuration of the weldment, i.e. on the difficulty of access for the probe.

–        The expanded time-base sweep should be chosen so that a triple traverse is displayed on the screen. The sweep may, however, be modified according to the difficulty of access and to the welded joint.

–        Scanning for longitudinal defects (aligned in the direction of the welded joint) is performed by a transverse displacement of the probe with respect to the axis of the weld. The lateral displacement of the probe, which depends on the dimensions of the transducer, should be such as to ensure the over-lapping of the scanned areas; see Figure 9.

–        When an anomaly has been detected, the weld may be inspected further by moving the probe parallel to the weld and swinging it back and forth by la to 30°. Then the speed of time-base sweep may be set for displaying an ultrasonic path equal to a double traverse.

–        For scanning flush welds one may place the probe on the centre line for the welded joint and direct the ultrasonic beam along the longitudinal axis of the weld.





1.3. Pressure and Tightness Tests

Pressure or tightness tests are required during ship construction and thereafter at periodical surveys or after repairs when the tightness of the respective section(s) has to be proved again.

For such tests the methods are different for either ship tanks and/or cargo tanks.

1.3.1 Basic requirements for tanks (except cargo tanks)

All ballast, trim, feed water, freshwater, and heeling tanks as well as oil tanks for fuel and lubricants, shall be pressure tested by water corresponding to a water column of 2.5 m above the upper tank level; under certain circumstances a pressure test with air followed by a later function test with the liquid is allowed.

Should the deep load line be higher than 2.5 m above the upper level of the tank, the tightness is to be tested with a water column corresponding to the deep load line.

In all cases the testing shall be carried out with a water column reaching to the uppermost level of the overflow or air pipe.

1.3.2 Pressure test of cargo tank

Pressure/tightness tests of cargo tanks of oil and chemical tankers, cargo tanks on dry cargo vessels, etc. are to be carried out as follows:

Prior to the vessel’s launching a tightness test should be carried out by water pressure in the cargo tanks and cofferdams. This test is to be carried out in such a way that the cargo tank bulkheads and the cofferdam bulkheads are tested at least from one side. The test shall be carried out prior to the application of the first protective coating.

Should the test with water not be possible during the vessel’s stay at the vessel 15 building place or dock, hydrostatic pressure test can also be carried out after launching.

For cargo tanks the test requires a water column corresponding to 2.5 m above the upper level of the tank. Any specific weight of the cargo above 1.025 t/m3 has to be taken into account.

For cofferdams a water level up to the upper edge of the access hatch is sufficient.

1.3.3 Tightness test of hatch cover

Weather deck hatch covers should be tested for “weathertightness”.

These tests should usually be carried out by hose testing using a fireline with a nozzle of 12.5 mm diameter at a pressure of at least 2.0 bar from a distance of 1.5 m.

1.4 Function Tests

Function tests or operation tests should prove by demonstration that the tested component

–        fulfils its respective purpose under the conditions for which it is designed, and that

–        all relevant aspects of safety are satisfied when the component is in operation, in open and/or closed position.

1.4.1 Basic requirements

Function tests shall be carried out with the Surveyor of the

Administration attending and the shipbuilder acting according to the following guidelines:

A definite testing procedure with details of all single tests is to be agreed upon, containing information on the duties and actions of all persons involved.

All relevant safety valves and/or pressure or temperature or flow control s should be readjusted and checked in the workshop before field installation and testing.

For reasons of safety the following should be considered and provided:

–        means of escape,

–        good lighting, including emergency lighting,

–        shipboard electricity in function and backed up, including blackout back-up,

–        means for fire fighting to be ready,

–        the persons engaged in testing shall be limited to a minimum number,

the testing director shall be selected and nominated.

1.4.2 Items to be tested

The following should be considered for each function and/or operation test:

–        Testing of all operational conditions under which the system should prove safe operationability (such situations may also be simulated ).

–        Testing of all relevant means of built-in control s, indicators, valves, and fittings; tightness of respective piping, admissible motor load, etc.

–        The minimum or maximum data expected; the relevant limits should be reached and demonstrated.

1.4.3 Hull function tests

Function tests forming part of hull surveys are inter alia:

–        anchoring tests

–        mooring winch tests

–        hatch cover operation tests

–        cargo gear load tests

–        maneuvering tests

–        bollard pull tests

–        heeling tank tests

–        accommodation ladder tests

–        pilot lift tests

–        cargo lift tests

–        cargo ramp tests

–        cargo door tests

1.5 Inclining Test

For each new building or after each modification of the vessel which influences stability an inclining test is to be carried out prior to sea trials for the vessel’s recommissioning into service. This test is to be carried out with the Surveyor of the Administration attending and under suitable conditions.

1.5.1 Condition for testing

–        Tanks should be empty and the vessel more or less in a completed state in respect of installation work and the equipment installed. Unavoidable tank contents should be concentrated to a tank with vertical side walls.

–        The additional weights on board shall not exceed 20% of the lightweight, provided no other stringent reasons request a higher percentage for additional weights.

–        Tanks should be completely filled up to 100%. Should a tank be partly filled, the free surfaces must be such that they do not change considerably during testing.

–        Vessels must be free of persons which are not actually carrying out testing and control measurements.

–        The vessel should be unlimited in movements, i.e. mooring rape free and no contact to quay walls.

–        Cooling water, fire fighting, sanitary, fuel, lube oil systems should be filled up to operational conditions.

Ditto boiler and cargo cooling or hydraulic systems.

–        Wind and current should not affect vessel’ s free movement during the test.

1.5.2 Testing procedure

–        The inclination angles should be between 1.5º and 2.0º In any case limits of 1.00 and 2.500 have to be maintained. The inclinations to each side should be carried out twice. The zero points should be noted in the protocol.

–        The inclination test is to be calculated by using the hull form data for the actual waterline (buoyancy with trim correction).

–        Inclining tests can be omitted for sister vessels of the same type built by the same shipyard without deviation of building data which could influence stability, provided the test results of two previously built vessels produce comparable results. For this the written approval of the owners (and possibly of the Administration) is required, but a deadweight calculation is to be carried out in the presence of the Surveyor for the Administration.

–        If applied for, the inclination test can be omitted with huge tankers and bulk carriers of a length of above 250 m provided again the ship owner (and possibly the Administration) approves this in writing and the deadweight calculation is carried out under the attendance of the Surveyor of the Administration.

–      For vessels with built-in heeling moments, f.i. with cranes at one side only, also this moment is to be calculated in connection with the evaluation of the inclining test.

1.6 Thickness measurements

1.6.1 Anchor cables

Anchor chains are usually measured by using caliper slides.

Chain links in the vicinity of the chain ends should be measured in 2 cross sectional directions.

The locations for measurement must be chosen at the link ends where maximum wear and/or deformation is to be expected and/or visible.


1.6.2 Thickness measurements of hull scantlings

In general, thickness measurements are made by ultrasonic thickness gauges (see above 1.2.4).

If carried out professionally and in a representative way, measurements of the actual thickness of scantlings can generally reveal the actual overall condition of a vessel with respect to its structural strength.

The scope of the measurements required is determined by the rules of the classification society based on the type and age of a vessel under survey. The actual conditions of the structure, verified by visual observations, may request premature and/or additional measurements.

As a general rule, the smaller the thicknesses the more the extensive measurements have to be.

In areas of heavy corrosion testing is to be increased to show the extent of wear and to allow proper judgment if the area is to be renewed or otherwise repaired.

1.7 Vibration Measurements

Detailed vibration investigations should be made during the design period of a vessel to predict the vibration levels in accommodation and working spaces and to avoid damage by excessive accelerations to hull structures and machinery.

For vessels with slow-speed 2-stroke engines an overall vibration examination should be carried out for hull and superstructure.

Vibrations can be excited by periodical forces, such as the main engine (as a function of the firing frequency), the periodical propeller blade force s at blade frequency, and other free vibrating masses.

Tank sides and shell plating areas in way of the engine room and propeller area should be designed so that structural frequencies are higher than the respective exciting frequency.

For vessels with medium speed engines the possibility of propeller blade induced vibrations should be examined. This type of engine induces excitations with firing frequencies between 23 and 33 Hz. Calculations, of natural frequencies of local structures are therefore necessary.

Whether other systems as masts, rudder arrangements or shaft-lines are to be investigated, depends on the individual case.

Local structures should have’ natural frequencies of about 20 – 25% above the highest main exciter frequency. Such calculations may be carried out by using simple formulas, or by the finite element (FE) methods.

FE models which are used for strength calculations may also be utilized for the vibration analysis.

Classification societies can greatly assist ship-owners or builders with such calculations which may avoid expensive modifications or structural alterations after unfavorable seatrials.

Vibration measurements are usually carried out in new-buildings during sea trials.

Occasionally these measurements are not sufficient and have to be repeated in a fully or partly loaded condition of the vessel and occasionally also under certain engine operation modes.

Measurements are then carried out by a special surveyor team, using vibration registration equipment positioned in specially selected locations to record simultaneously engine operation modes together with local structural excitation frequencies, amplitudes and acceleration in order to identify resonances.


The recognized Classification Societies have developed systematic hull inspection programs which ensure that a vessel’s structural parts, components and compartments are duly kept under control by periodical examinations and are subjected partially or totally to the above described visual inspections, testing and examination methods.

These survey programmes are:

–        Periodical Class Renewal procedures after 4 years, with a possible extension to 5 years if satisfactorily subjected to a class extension survey;

–        Continuous Survey procedures for Hull (CSH) with the renewal survey program divided into partial inspections of abt. 20% for each year) over a period of 5 years;

–        Class Extension Surveys

–        Dry-docking Surveys at intervals of at least 2.5 years.

All these scheduled inspection systems ensure that a vessels condition is regularly controlled and properly supervised within the respective survey system.

The respective inspection schemes are as follows:

2.1 Periodical Class Renewal Surveys (also called “Special Surveys”)

For the Renewal of the Class, the ship’s hull, machinery including electrical installations and the automatic/remote control systems are to be subjected to surveys at the fixed intervals.

A class renewal survey can, under special circumstances, be carried out in several steps. Here, the total survey period must not exceed 12 months.

A bottom survey within this period of time can likewise be recognized if the requirements for class renewal are fulfilled.

The examination of certain covered parts may be dispensed with at a Class Renewal Survey if the Surveyor is completely satisfied of their efficient condition, and if the Owner undertakes to have them exposed for examination within 12 months. A corresponding entry will be made in the Certificate of Classification.

Class Renewals Hull is to be effected in the sequence I, II, III, IV and subsequent to IV. The Class Renewal, No. IV and the following correspond to Class Renewal III.

2.2 Continuous Survey Hull – CSH

Instead of the Class Renewal procedure according to 2.1 the Owner may apply for Continuous Class Renewal for Hull and Machinery. The Class Renewal procedure can, however, also be adopted only for the hull or only for the machinery, including the electrical plant.

The required surveys under CSH extend over a period not exceeding

5 years. It has to be made sure that during the Continuous Surveys all parts of the ship’s hull and/or machinery, including the electrical plant, be surveyed at intervals not exceeding the periods normally required for the maintenance of class.

The Surveyor may re-inspect compartments or structures are deemed necessary.

At the end of the period of class the extent of survey of the hull depends on the scope of the respective class renewal due, I or II or III or IV.

Where both, a ship’s hull and machinery, including the electrical plant, are surveyed in accordance with the continuous class renewal procedure, the 5 years’ period of class is valid for both sectors. This is conditional upon the prescribed survey intervals and respective scope of survey required being observed.

Where either only the hull or the machinery, including the electrical plant, is subject to the continuous class renewal procedure, a 4 years’ period of class is valid for both sectors. Class extension by 12 months is possible. Surveys according to the continuous class renewal procedure are performed al so during the period of class extension.

2.3 Class Extension Surveys

On Owners’ request el ass can be extended by not more than 12 months after survey of the vessel – at least to the scope of the requirements for an Annual Survey afloat. Class may be extended only if hull and machinery, including the electrical plant, are in perfect condition and if, since the bottom was last surveyed, no incidents occurred resulting in damages expected to have been caused to the underwater body.

Ships having a character of classification different from 100 A 4 (highest GL class character) cannot have their class extended.

Dry-docking intervals are to be observed for class extensions.

At a Class Extension Survey the ship is to be inspected, if practicable, when it is not loaded, so that the hatches, the cargo holds, the tweendeck spaces, the watertight doors, etc. can be examined; if necessary, tanks will also be examined. In the case of oil tankers and ships carrying combined cargoes (e.g. OBO-ships) the ballast tanks located in the cargo area will be subjected to a general condition survey. An inspection of the machinery, including the electrical plant, is to be made to verify, in particular, satisfactory operation. Automatic/remote control systems are to be examined, taking into account records of operation.

2.4 Docking Surveys

Underwater hull inspections at regular intervals shall ensure that the outside and the steering facility of a ship remain in a satisfactory condition. Such inspections are also carried out for the control pf the propeller, the shaft-line bearings and seals. In addition inlet and outlet piping, valves, seachests and sea filters are examined.

A special type of underwater hull survey is the “in-water survey” which can be applied under special considerations.

For seagoing ships with character of class 100 A 4 an in-water survey may be recognized as a substitute for every second periodical bottom survey, provided

–        the required special equipment is available, documents have been issued and trial requirements complied with and if the survey is carried out as required and with approved firms and satisfactory results,

–        this survey is not part of a class renewal.

For ships of more than 10 years of age the intervals between dry-docking must not exceed 2.5 years.


Special Thanks to Capt. Harry González



Comprehensive Guide to Marine Survey

Cargo-Ship-marine-surveyMarine surveyors perform inspections of vessels of all types including pleasure craft, passenger vessels, tugboats, barges, dredges, oil rigs, ferries, cargo vessels and warships, as well as marine cargo, marine engines and facilities such as canals, drydocks, loading docks and more for the purpose of pre-purchase evaluation, insurance eligibility, insurance claim resolution and regulation compliance.

Surveys typically include the structure, machinery and equipment (navigational, safety, radio). Marine surveyors also are involved in other aspects, including confirming compliance with international treaties associated with such things as pollution, international security, and safety management schemes. They may also examine cargo gear to ensure that it meets the requirements or regulations.

Marine surveyors may perform the following tasks:

  • examine and approve design plans of hulls and equipment such as main propulsion engines, auxiliary boilers and turbines, electrical power generating plant, refrigeration and air conditioning plant and pumping systems
  • inspect standards of construction and witness tests of materials
  • inspect hulls, machinery and equipment during ship construction to ensure standards and legislative requirements are met
  • conduct surveys throughout the ship’s life to ensure standards are maintained
  • perform inspections required by domestic statutes and international conventions
  • witness tests and operation of emergency and safety machinery and equipment
  • measure ships for tonnage and survey them for load line assignment
  • attend court as an expert witness and assist in coronial enquiries
  • investigate marine accidents.


Classification Society Marine Surveyor

A classification society marine surveyor inspects ships to make sure that ships, components and machinery are built according to the standards required for their class, and examines accident damage.

Government Marine Surveyor

A government marine surveyor inspects ships to make sure that ships, components and machinery meet crew and passenger safety regulations and construction standards. They may also assess and approve safety reports and plans as well as examine candidates for certificates of competency.

Private Marine Surveyor

A private marine surveyor examines ships and their cargoes, investigates accidents in port and at sea (e.g. oil spillages) and prepares accident reports for insurance purposes.

Well, sometimes the surveyor must enter confined spaces.
Work in confined and enclosed space has a greater likelihood of causing fatalities, severe injuries and illness than any other type of shipyard work or onboard ships.

The key hazards associated with confined spaces are:

  • Serious risk of fire or explosion;
  • Loss of consciousness from asphyxiation arising from gas, fumes, vapor or lack of oxygen;
  • Drowning arising from increased water level;
  • Loss of consciousness arising from an increase in body temperature;
  • Asphyxiation/suffocation arising from free flowing solid (engulfment) or the inability to reach a breathable atmosphere due to entrapment.

Likewise, the Surveyors will routinely enter confined spaces that are difficult to access due to small and/or narrow openings. There may be physical constraints within the space which need to be considered, and the space itself may be cramped permitting only restricted mobility.
Given the usual enclosed and darkened nature of a confined space this activity ideally should not be carried out by personnel suffering from phobias (e.g. claustrophobia) or who are susceptible to panic or anxiety attacks.
For further details regarding hazards in confined spaces see Annex, section 2, Confined Space Hazards.


  • Do not enter a space first or alone!
  • If in doubt – do not enter – no survey is worth risking life or health for.

Rol of Surveyor

Prior to the survey, he surveyor should review the ship’s file.  He must verify the class and statutory position.

He must be aware of the rules and procedures that are involved in order to satisfactorily complete the survey.  When he goes on board the ship, one of the first things he must do is to check the certificates.  The true class position is not what is shown in equaisis, but what is on board the ship, and therefore the certificates are the first thing that must be checked.  He should compare the position on board with the position he found in equasis.  If there are any inaccuracies, he must report them to the Main Office as soon as possible in order that the computer is up dated accordingly.

He must ensure that there are no overdue recommendations or surveys.  If there are, he must approach the owner’s representative, the captain or the superintendent, to see that they are performed.  He cannot leave the ship with overdue surveys or overdue recommendations.  This is very important.  He should explain the survey scope and schedule with the owners, i.e. the Captain, Chief Engineer Officer or the Superintendent.

A badly planned survey means a lot of wasted time and frustration.  Remember that the crew are not there just to cater to the needs of the surveyor.  The ship is in port to load or discharge a cargo.  The crew have their functions; they cannot suddenly drop everything to launch a lifeboat.  So it is very important that the surveyor plans the surveys with the owner’s representative.  He must explain what he is going to do, whether he needs any tanks to be opened up, whether he wants any tests performed.  And he must agree the schedule with the owners.  If this is done, it will speed up the survey and give a very good impression to the owners, and establish a good working relationship.  If not, everyone is frustrated and angry.
Surveyor Safety

General Precautions
The surveyor must be suitably dressed for the space to be inspected. This means that if he has to go into dangerous spaces, he must be suitably dressed, in a boiler suit, with the right shoes, gloves, and hard hat.

Remember, the boiler suit must be in good condition and reflect the quality of our Society.

When the surveyor is on a tanker, shoes should be such that they will not give off any sparks if struck against steel. The surveyor should carry a suitable torch, again depending on the space to be inspected this may have to be a gas proof torch. In an ordinary hold, where there are no problems with dangerous or flammable gases, it may not be necessary to use such a torch. But when going into compartments that might contain dangerous or flammable gases, a gas proof torch must be used.

When conducting machinery surveys, the surveyor must be aware in case any of the contents of his pockets fall into the machinery itself. The surveyor must never start any machinery or accept alarms, this is the responsibility of the crew.

The surveyor has to climb around the hold or the ship’s side, and if the scaffolding is in poor condition there is danger that he may fall, or knock a piece of steel over which could fall on to somebody’s head. If the timber of the scaffolding is in bad condition, too narrow or badly fixed, the surveyor should decline to perform the survey until the scaffolding is put right.

Hatch covers can also pose a problem, particularly wooden hatch covers with canvas stretched across them. One cannot see whether the hatch board is there. If you are walking or planning to walk on wooden hatch covers, make sure that all hatch boards are in position.

Similarly, when climbing or going down ladders, if the ladder rungs are missing or in very bad condition, they should be repaired, because they are dangerous and affect the safety of the surveyor. In icy conditions, ladders or platforms can be very slippery and very dangerous. This is particularly the case if you are going into an oil tanker or tanker, and the steel is coated with a veneer of oil, which can
be very slippery and very dangerous.

Quite often, if a ship is under repair, deck plates are removed and no protection or prevention is erected to stop anyone falling down a hole. Obviously when you are going around a ship you have to pay particular attention to this, especially where the ship is under major repairs in a shipyard. Similarly, the surveyor must be aware of the dangers of the temporary cables and pipe lines that are necessary for the repairs.If he is conducting a survey and people are working above him, he must be careful, because anything could fall, and if he is not wearing a hard hat or is not suitably protected, this can be very dangerous.

On a heavy‑lift ship when they are making a heavy lift, he should not be in holds or tanks or confined spaces.

In the event of an accident during the heavy lift, the ship could roll and this could seriously affect the safety of anyone inside confined spaces. Electrodes and welding give rise to very high‑intensity light. If you look at welding without protective eyeglasses, then you can damage your eyesight. In mild cases the damage is temporary, but extremely uncomfortable. In serious cases, there can be permanent eye damage. There is always welding on board, and he should be careful at all times.

Never conduct a survey alone, or when the shipyard has closed, or there are no workers around. If the surveyor becomes trapped in a compartment, or falls, and no one knows where he is, then he could remain there indefinitely, with serious consequences.

Carrying out internal inspections in poor lighting is also very dangerous. First, he cannot see to survey properly, but it is also dangerous walking around there could be a lighting hole not protected, and he could fall.

The same goes for the slippery surface of a tank, caused by oil or other products. A slip could prove fatal.
Open manholes, stringer plates, all may be dangerous if the surveyor is not looking where he is going, concentrating on the inspection he may forget where he is putting his feet. Handrails and ladders become corroded and weakened, be careful using them.

When a ship is in a shipyard, the shipyard invariably has its own safety regulations and requirements. These Regulations should be strictly observed. Similarly, on a ship, it may have its own safety regulations that must be carefully followed.

If the surveyor is in a tank, and experiences any slight dizziness or lack of balance, this is the initial warning of oxygen deprivation, and he should leave the compartment immediately. Do not hang around. He must exit into the fresh air, and ask for the compartment to be properly ventilated before he can resume his surveys.

The optimum oxygen level is between 20.8 and 21 per cent. When it goes below 20.8 per cent, there are dangers of asphyxiation. If there is 10 per cent combustible gases present in the atmosphere, that is enough for an explosion. When entering cargo tanks of oil tankers, or bunker tanks, or anything tank that has carried combustible liquids, the surveyor must be careful and ensure that the tanks have been tested before entry.

For Crude Oil Washing, the oxygen content has to be less than 8 per cent. If entering a cargo tank that has been cleaned the surveyor must make sure that the tank is well ventilated, because the oxygen level in that tank will be below 8 per cent and well below the 20.8 per cent minimum. It has to be ventilated, to avoid any pockets of low oxygen.

For toxic levels (this applies more to chemical tankers) you have to follow the rules that will be discussed later.

With a very sour crude oil, there may be high contents of hydrogen sulphide, which is the bad egg smell remembered from chemistry at school. It requires only 10 parts per million for it to be dangerous. When entering a tank, if the surveyor notices that smell, verify the safety of the tank.

If benzene is present, again only 10 ppm is needed. Please refer to the attached notes on this slide, which contain additional information to be taken into consideration. This may be briefly explained as follows: all vessels should have a safety data sheet for the cargoes that they are carrying. These apply not just to the various cargoes, but products such as fuel oil, lubricating oil, boiler chemicals, etc. The data sheet shows the necessary characteristics of the material, as well as information for safe handling, and actions to be taken into the event of spillage. It also provides information on first aid and the tolerance vapour limit (TVL) in ppm.

The TVL is a maximum concentration of the chemical that can be safely inhaled: once that level is exceeded it is dangerous. The surveyor must bear in mind that it can be dangerous to his health. He can be permanently injured by it, or even killed.

Some chemicals require antidotes to be carried on board. If he is are carrying out a survey on a chemical tanker that has carried or is carrying dangerous cargoes, he must be extremely careful in case there is any residue or leaks from an adjacent tank. Everyone should be familiar with the chemical in question, and with safety requirements. The Captain will have a log of cargoes carried, the surveyor must check this as part of his documentation check and before he commences his surveys.

Spaces which are low in oxygen (i.e. less than 20.8 per cent) include heavily corroded ballast tanks. A reduction in the oxygen level can occur as rusting is a process of combustion, which absorbs the oxygen present in the atmosphere, forming carbon dioxide. If there is a badly corroded ballast tank, which has not been properly ventilated, there can be pockets of air which contain substantially less than the 20.8% minimum.
Similarly, if ballast tanks are partly filled with seawater, and this has been sloshing around, the seawater will absorb the oxygen, and again there can be a reduction in the oxygen in the atmosphere. The same applies to fresh water tanks. So when going into these tanks, if there is water present, he must be careful, and make sure that the tank has been properly ventilated.

Void spaces are another area that can cause concern. These have probably been coated, the compartment is closed and rarely visited and ventilation is limited. When entering such a compartment that has not been properly ventilated, it can be dangerous.

Entering any of the double bottoms, the surveyor should always ensure that there are two manholes opened, so that there is a natural current of air through the compartment during inspection.

Be careful when going into the crankcase of a main engine that have just been stopped. The air inside the crankcase can be very low in oxygen, the surveyor should make sure that the crankcase is well ventilated before entry with at least two doors removed.

When entering confined spaces, always check when they were opened, how long they have been ventilated, and the ventilation arrangements during the survey. If it is a compartment that is likely to contain gas, giving off flammable or dangerous gases, there must be continuous ventilation and regular checks

Pay attention to the surrounding compartments, because if there is a crack in the bulkhead, even only a small one, and the adjacent tank contains a hazardous chemical, this can be very dangerous, because small amounts of chemicals can produce a lethal atmosphere. When boarding a chemical tanker in particular, always check void spaces around LNG tanks. Again, be very careful.

Check the nature of the last cargo contained in the cargo tank. What is the condition of the tank, if it’s a ballast tank, is it badly rusted, and so on? All these points must be borne in mind prior to his entry he must make sure that everything is all right. It is too late when the surveyor collapses in the bottom of the tank to realise that there is a problem.

When going into any confined space, the surveyor must verify the communication arrangements. How does he communicate with the outside? If there are problems, he needs to raise the alarm as quickly as possible, and so it is necessary to have an efficient form of communication. Before entering a compartment, or tank, always review the tank entry permit or certificate. When was it issued? When is it valid to? By whom was it issued? Equally important is when the compartment has to be verified again, because if the survey will extend past the time of verification, the surveyor should insist on the verification being done before he enters the tank. This is very important for his own safety.

Tankers have what is called ISGOTT (International Safety Guide for Oil Tankers and Terminals) Regulations, these must be observed whenever he is on board the ship. They lay down very strict regulations with regard to tank entry, operational visits, cleaning tanks, and so on. These regulations apply when the ship is alongside and when it is at sea. Great care should be exercised that these regulations are very carefully followed.

Check the isolation of the compartments. Inert gas lines should be blanked, or valves closed, marked, and secured. The surveyor should always make sure that there are two valves between him and any pressure. If one valve is leaking, he could be in a serious situation before he realises it.

The pressure vacuum valve lines should be blanked, or closed, marked and secured. If he is in doubt about a valve and its condition, he must insist on blanks being inserted. The crew must make sure that they are removed on completion.

The same applies to the cargo, ballast and drainage lines. The surveyor must always make sure that there are two valves closed because he doesn’t want to be inside a cargo tank when somebody makes a mistake, and the wrong valve is opened and oil or ballast or oily ballast is allowed to enter the tank. This bring would bring in a lot of gas as well and it can be extremely dangerous and harmful. If in doubt they should be blanked off as necessary?

The surveyor should ascertain the contents of the adjacent compartments. If they are they filled with toxic or flammable material precautions should be taken because there could be dangers due to cracks or leakage into the compartment being surveyed.

At sea or in harbour, the captain or a person assigned by him will issue the entry permit for the compartment. That person should be trained, and should have suitable equipment to verify the condition of the air. The equipment should be tested periodically, to verify its accuracy. The instruments must be periodically tested by an approved organisation.

The surveyor must make sure before he goes into a compartment, that its access has been authorised by the right person, and that the equipment he has used has been properly tested. When entering dangerous compartments where even an extremely small amount of gas is present which would be seriously harmful to your life, it may be necessary for you to wear breathing apparatus. In this case, make sure that the apparatus is in good condition, the lifeline is properly secured, and a means of communication arranged.

Adjacent spaces or associated areas are considered as dangerous spaces, and every time he enters into one of them, there must be a gas‑free certificate for safe access. This usually lasts for about three hours, assuming normal ventilation, but the certificate must be valid for the duration of the survey.

Spaces designed to carry toxic materials ‑ obviously including loading areas, because there can be toxic material present through leakage of the loading lines ‑ must be considered as dangerous. If the toxic gas requires that the surveyor wears a breathing apparatus, then he must do so. There is special equipment for testing toxicity present in the compartment. These are known as Draeger Tubes, there must be one type for each of the various chemicals or materials carried. The ship should have an adequate supply of these and should be used for testing prior to access.

A compartment can have sufficient oxygen, but it may contain a toxic gas that will still kill. The surveyor must make sure, depending on the type of vessel and the cargoes that have been carried, about the condition of tanks before he goes in.

When entering boilers, a similar problem can occur. When both manholes have been opened, and the boiler well ventilated, there should be no danger. But the surveyor should not go into a boiler with only one manhole open, unless it has been very well ventilated.

If there are other boilers on line, it is vitally important that he checks that all valves are closed between him and the other boiler. There should again be at least two valves. This is particularly true in the case of high‑pressure boilers. In fact, it may be necessary to insist upon on a suitable blank being inserted, to prevent the possibility of any superheated steam leaking into the boiler when conducting a survey. Steam will also kill you, not just from suffocation, but from scalding.

The captain or a person assigned by him will issue the entry permit for the compartment when the vessel is at sea or in harbour. That person should be trained and have suitably calibrated equipment to verify the condition of the air. In port, repair yard this would normally be issued by a Certified Marine Chemist or Industrial Hygienist. The surveyor must not be involved with the issuance of Safe Entry Certificates. This will avoid the surveyor being held responsible in case of an accident.

Safe Working Practice (A) 

The person shall test all spaces to be entered using a calibrated, direct reading instrument for the following:
Oxygen Content
Flammable gases and vapours
Potential toxic air contaminatnts
Hydrogen Sulphide (where applicable)
On completion he should issue an entry permit that contains the following: date and time of test, space tested, results (oxygen, combustible gas, toxics, visual examination), instrument used and date of its calibration, name of competent person.

Safe Working Practice (B) 

In addition to the Safe Working Practice (A), extenuating circumstances may require the following:

Persons with operational Self Contained Breathing Apparatus and life lines. Persons to be stationed outside the tank with lines of communication established and clearly understood.

The surveyor to be provided with an Emergency Escape Breathing Apparatus.

A competent person equipped with operating atmospheric monitoring devices.

Remember the surveyor must never go into a compartment without proper communications and security. Safe working practices must be followed very carefully.
If the surveyor goes rafting in a cargo tank of a tanker, to perform the close‑up survey of the cargo and ballast tanks, the raft must be in good condition with sufficient number of compartments to provide adequate buoyancy and stability in the event of any damage and rupture. It must be made from heavy-duty material.

The tank must be suitable for rafting in that it is not too narrow or the structure such that it would easily damage the raft.

The surface of the water must be calm and free from waves. Any swell, the water level must not be expected to rise more than 0.25 m. No tank should be entered if filling is still in progress, the water level must be either stationary or falling.

The surveyor must check that the surface of the water is clean, and that there is no oil present. Even a small film of oil will give off gas, which could have a serious effect on the condition of the air in a confined space like that.

With the ship rolling slightly, or the movement of water inside the tank, oxygen will also be absorbed more quickly.

All conditions of entry into a confined space must be observed. The entry permit must be valid for the duration of the survey.

The level of the water should be such that the surveyor never puts himself in the position where he could be cut off. In other words, if the level of the water in the ballast or cargo tank reaches the level of the lower edge of the underdeck beams, the peak beams, this is too high, and he should not go in. During the survey, if the surveyor sees that the level is rising he should exit as quickly as possible. Remember, the water level should be stationary or falling to avoid being trapped in the tank. At no time should the water level come within a metre of the deepest underdeck web.

Any communications with the inert gas system or pressure vacuum system should all be blanked, or two valves must be closed, marked and secured.

Obviously, before going into any compartment, a safety meeting is conducted with the personnel to discuss communications, safety, and recovery of people in an emergency.

The lines of communication must be tested and suitable for the compartment being entered. Ensure adequate safety lighting available, as the surveyor will not be able to see defects if the lighting is poor. The raft should be properly secured, to ease retrieval.

There should be somebody on the ladder who can see the raft at all times, and of course all personnel on the raft should be fitted with lifejackets and hard hats.

Whenever the surveyor enters any tank the rescue equipment should always be immediately available. It should be outside the tank, adjacent to the entrance, so that in any emergency it can be used immediately, and people rescued quickly. Speed is of the essence. The surveyor should check that it is in position before he enters the tank.


Special Thanks to Capt. Harry González