Capt.S.S.Chaudhari

Grain Carriage

A brief history of grain regulations: –
Bulk grain because of its semi fluid property is liable to shift during heavy rolling at sea. A shift of grain can cause a vessel to list to a dangerous degree. She may even capsize. Because of this hazard, regulations concerning the loading and carriage of grain have been in force for many years. SOLAS 1948 grain regulations required extensive use of expensive temporary fittings and/or bagged grain.

1960 regulations appeared relaxed. They were less expensive to carry grain than those adopted by SOLAS and therefore many countries supported them. Though, the Convention itself did not enter into force until 1965. The regulations mainly aimed at restricting the movement of grain by installing temporary centerline shifting boards, feeders in hatchways, saucers and by over stowing of bulk grain bagged grain or other suitable cargo. Several ships loaded under the 1960 SOLAS rules were lost at sea probably because 1960 Convention had underestimated the amount of “sinkage”. The regulations placed an over reliance on the ability of hatch feeders to eliminate under deck voids. Though, geometrically the voids formed are still very large. The regulations did not adequately consider the potential for a grain shift due to these voids. The inherent stability characteristics of the individual general cargo was always an important consideration.

IMO Assembly in 1969 adopted new grain regulations [resolution A.184 (VI)], which became known as the 1969 Equivalent Grain Regulations. These regulations were more practical and economical than the 1960 and were subsequently incorporated into the 1974 SOLAS Convention. IMO resolution A264 (VIII) revoked Resolution A.185(VI). This resolution caused amendment to chapter VI of SOLAS 60.

At its 5th session the MSC by resolution MSC 22 (59) adopted amendments to SOLAS 1974, including chapter VI. Chapter VI was now to be supplemented by Grain Code, that took effect on 1st Jan 1994. Thus provisions of A264 (VIII) would remain in effect for States party to 1960 SOLAS but not to 1974 SOLAS.

Grain Code:-
It applies to all ships – including existing ships and those of less than 500 gross that carry grain in bulk.  Part A contains special requirements and gives guidance on the stowage of grain and the use of grain fittings.  Part B deals with the calculation of heeling moments and general assumptions.

Presently chapter VI of SOLAS deals with “Carriage of Cargoes”. This chapter is divided in 3 parts. Part A (SOLAS) is General Provisions. Reg. 2 of this part “Cargo Information” partly deals with the carriage of bulk grain. Thus, “The shipper shall provide the Master or his representative with appropriate information on the cargo sufficiently in advance of loading to enable the exercise of precautions which may be necessary for proper stowage and safe carriage of the cargo. Such information shall be confirmed in writing and by appropriate shipping documents prior to loading the cargo on the ship. In case of bulk cargoes, information shall be on the stowage factor of the cargo, the trimming procedures, likelihood of shifting including angle of repose, if applicable and any other relevant special properties.

IMO Assembly in 1969 adopted new grain regulations [resolution A.184 (VI)], which became known as the 1969 Equivalent Grain Regulations. These regulations were more practical and economical than the 1960 and were subsequently incorporated into the 1974 SOLAS Convention. IMO resolution A264 (VIII) revoked Resolution A.185(VI). This resolution caused amendment to chapter VI of SOLAS 60.

At its 5th session the MSC by resolution MSC 22 (59) adopted amendments to SOLAS 1974, including chapter VI. Chapter VI was now to be supplemented by Grain Code, that took effect on 1st Jan 1994. Thus provisions of A264 (VIII) would remain in effect for States party to 1960 SOLAS but not to 1974 SOLAS.

Grain Code:-
It applies to all ships – including existing ships and those of less than 500 gross that carry grain in bulk.  Part A contains special requirements and gives guidance on the stowage of grain and the use of grain fittings.  Part B deals with the calculation of heeling moments and general assumptions. Presently chapter VI of SOLAS deals with “Carriage of Cargoes”. This chapter is divided in 3 parts. Part A (SOLAS) is General Provisions. Reg. 2 of this part “Cargo Information” partly deals with the carriage of bulk grain. Thus, “The shipper shall provide the Master or his representative with appropriate information on the cargo sufficiently in advance of loading to enable the exercise of precautions which may be necessary for proper stowage and safe carriage of the cargo. Such information shall be confirmed in writing and by appropriate shipping documents prior to loading the cargo on the ship. In case of bulk cargoes, information shall be on the stowage factor of the cargo, the trimming procedures, likelihood of shifting including angle of repose, if applicable and any other relevant special properties.

PART C (SOLAS) is Carriage of Grain.  Reg. 9 deals with the requirement for cargo ships carrying grain. It states that in addition to any other applicable requirement of the present regulations, a cargo ship carrying grain shall comply with the requirement of the International grain code and hold a document of authorization as required by the code, thus making the code mandatory. A ship without such a document shall not load grain until the Master satisfies the Administration or the Contracting Government of the port of loading on behalf of the Administration that the ship will comply with the requirements of the International Grain Code in it’s proposed loaded condition.

So, basically vessel can load grain even without a DOA as per Reg 9.2 (SOALS, Ch VI Part C). It must be noted that due to vibration and movement of the ship at sea the grain settles down (by about 2% of its vol.) resulting in voids at the top of the compartment. Bulk grain has a low angle of repose. Angle of repose has relationship with the amount of roll and the inclination of hopper tanks. If the ship rolls to an angle greater than angle of repose, risk of grain shift exits. A slope of hopper tank more than angle of repose would make a hold self trimming.

Some important definitions

The term grain covers wheat, maize (corn), oats, rye, barley, rice, pulses, seeds and processed forms thereof, whose behaviour is similar to that of grain in its natural state.

The term filled compartment, trimmed, refers to any cargo space in which, after loading and trimming as required, the bulk grain is at its highest possible level.

The term filled compartment, untrimmed, refers to a cargo space which is filled to the maximum extent possible in way of the hatch opening but which has not been trimmed outside the periphery of the hatch opening owing to the following reasons:
1. DOA is provided by government owing to the structural arrangement say feeder ducts or perforated decks, etc are taken into consideration while calculating the void depths; or
2. The compartments are specially suitable where atleast 2 vertical or sloping grain tight bulkheads are fitted limiting the effect of transverse shift of grain.   

The term partly filled compartment refers to any cargo space wherein the bulk grain is not loaded in the manner prescribed as above.

The term angle of flooding (θf) means the angle of heel at which openings in the hull, superstructures or deckhouses, which cannot be closed weathertight, immerse. In applying this definition, small openings through which progressive flooding cannot take place need not be considered as open.

The term stowage factor, for the purposes of calculating the grain heeling moment caused by a shift of grain, means the volume per unit weight of the cargo as attested by the loading facility, i.e. no allowance shall be made for lost space when the cargo space is nominally filled.

The term specially suitable compartment refers to a cargo space which is constructed with at least two vertical or sloping, longitudinal, grain­tight divisions which are coincident with the hatch side girders or are so positioned as to limit the effect of any transverse shift of grain. If sloping, the divisions shall have an inclination of not less than 30° to the horizontal.

Intact stability Requirements: –
The intact stability of the ship carrying grain in bulk shall be shown to meet at least the following criteria after taking into account the assumed shift of grain. The assumed shift of grain is to an extent of 25° (15° for certain areas)

  1. The angle of heel obtained from a plot of the statical stability curve and heeling arm curve shall not be greater than 12° .The administration will provide a lesser angle than 12° if considered necessary.
  2. The residual area between the righting arm curve and the heeling arm curve up to an angle of 40° or the angle of flooding or the angle of maximum separation between the  two curves whichever is least shall be at least 0.075 m-radian ( not less than 0.075 m-radian)
  3. The initial GM shall be at least 0.3 m.

Before loading the bulk grain, the master shall if required by authorities, demonstrate the ability of the ships to comply with the stability criteria required by this section. After loading master will ensure the vessel is upright before proceeding to sea.

In the above fig

Stowage factor = volume per unit weight of grain cargo.
Displacement = weight of ship, fuel, fresh water, stores etc. and cargo.

The righting arm curve shall be derived from cross curves which are sufficient in number to accurately define the curve for the purpose of these requirements and shall include cross curves at 12 degrees and 40 degrees.

Regulation 10 of the code has recommendations in respect of stowage of bulk grain. It says that all necessary and reasonable trimming shall be performed to level all grain surfaces and minimize the effect of grain shifting. In any filled compartment, trimmed, the bulk grain should be trimmed to fill up under deck spaces to maximum possible extent.

In untrimmed filled compartment maximum filling shall be done in the way of hatch opening and allowed to stow at its natural angle of repose on the periphery. Unless account is taken of adverse heeling effect due to grain shift according to the grain code, the surface of partly filled compartment shall be secured so as to prevent a grain shift by over stowing. Alternately, the surface may be secured by strapping or lashing.

Document of authorization (DOA): –
DOA is dealt under regulation 3 of the code and is issued by Administration or Recognized Organization to every ship capable of being loaded in accordance with grain code. It shall be accepted as evidence that the ship is capable of complying with relevant regulations.

The document is accompanied with grain loading manual which enables Master meeting the grain stability criteria and has required information as provided in code.

A ship without DOA shall not load grain until the Master demonstrates to the satisfaction of Administration or Contracting Government of port of loading on behalf of Administration that vessel is loaded appropriately for the intended voyage. 

Regulation 9 of code deals with optional stability requirements for ships without DOA carrying partial cargoes of bulk grain. A ship without DOA may be permitted to load bulk grain provided

  1. Total grain weight does not exceed 1/3rd deadweight of ship.
  2. Filled compartments, trimmed shall be fitted with appropriate centre line divisions.  (Saucers may be accepted).
  3. All hatches to filled compartment, trimmed shall be closed and secured.
  4. All free grain surfaces are leveled, secured by overstowing, strapping / lashing or by securing with wire mesh.
  5. Through out the voyage GMo, after correction of free surface shall be 0.3m or that given by the following formula whichever is greater.

L is total combined length of full compartments (m), B the moulded breadth (m), SF the stowage factor (m3/t), Vd the calculated average void depth (m) &   the displacement in tonnes.

6. Master must demonstrate to the satisfaction of Administration or Contracting Government of port of loading on behalf of Administration that the ship will comply with the requirements of this section.

Voids exist above all free grain surfaces in filled compartments. The extent of the voids depends on the dimensions of the compartment and the depth from the overhead to the grain surface. Assumption is made in respect of void depth and the angle to which the grain surface will be with respect to horizontal.

Grain heeling moments are produced by a grain shift. Grain heeling moment is the product of the weight of the shifted grain multiplied by the horizontal distance between its initial and final centres of gravity. Grain heeling moments are expressed in tonne meters. Volumetric heeling moment is the product of the volume of grain that would shift multiplied by athwartship distance through which it would shift. It is common practice to calculate and tabulate the volumetric heeling moment of different compartments instead of weight heeling moment. A ship may load the grain of different stowage factors. To obtain the actual weight heeling moment for a particular grain the volumetric heeling moment is divided by the stowage factor of that grain.

Calculations of volumetric heeling moments
Volumetric heeling moments are calculated by naval architects and tabulated in the vessel’s approved grain booklet. The grain stability booklet is required for vessel engaged in the carriage of bulk grain. Calculations can be complex-depending on the geometry of the compartment. In approved grain stability booklet the volumetric heeling moments are represented for individual compartments in either curved form or in tabulated form enabling the use to find the volumetric heeling moments for the full and slack conditions.

A sample table of maximum volumetric heeling moment for partly filled compartment

In the table above only the maximum volumetric heeling moments for partly filled compartments are shown. 

Typical curves for volume, centre of gravity and volumetric heeling moment are provided for each hold: –
The curves for each hold are provided to give KG, volume and volumetric heeling moment for the cargo loaded and can be entered with the argument viz. depth from the tank top or ullage from the hatch coaming.

It can be seen that the volumetric heeling moment is zero at the base, maximum for half filled hold and minimal for the filled condition. KG for the present loaded condition can be obtained from the graph but KG for the complete compartment (geometric centroid) can be obtained from the tables.

Allowance for a vertical shift or grain: –
When grain shifts on a ship there is a net vertical upwards movement of the center of gravity of the grain which in turn raises the center of gravity of the ship and reduces the GM. In calculating the vessel’s stability the allowance for this is made in the following manner:

In filled compartments untrimmed no compensation is necessary and the KG must be always read from the tables, which is given for the full compartment. For the filled compartment if trimmed there appears to be an error or ambiguity. As given in B 1.1.3 of grain code CG of grain in case of a filled compartment trimmed shall normally, be based on assumption that the CG of grain is at volumetric centroid of compartment. It further says that, in cases where Administration authorizes a (further) accounting for the adverse effect of vertical shift is done by multiplying VHM by 1.06.

Some countries however strictly maintain that in any filled compartment if volumetric centroid is used no allowance is made to VHM. A factorof 1.06 is used if centroid of cargo is used. In partly filled compartments the transverse volumetric heeling moments are increased by multiplying the same with factor 1.12, if the KG of the cargo is picked up from the curve for actual ullage / sounding.

Table of allowable heeling moments: –
Table of allowable heeling moments is a ready reckoner table where Master can at one glance know whether the grain stability criteria would be satisfied for the proposed cargo distribution. The grain stability booklet contains tables of maximum allowable heeling moments, compiled for a wide range of combinations of displacement and KGv. These tables are usually generated by computer using input data from the vessels cross curves of stability. A sample of such table has been shown in the following example:

Ex. 1 M V Grain Product has a light displacement of 5110 t. free surface moments 920t-m. Grain of SF 1.28m3.t is loaded into the holds as follows:

Hold No 1        ullage 2.8m
Hold No 2        ullage 0.0m
Hold No 3        ullage 0.0m
Hold No 4        ullage 0.0m
Hold No 5        ullage 4.3m

KG for the full compartments was taken for centroid of entire hold space and for partly filled compartments the KG of the actual loaded cargo was taken. The VHM for filled compartments = 2100m4.The VHM for partly filled compartments = 3121m4.

Soln: In the example below the procedure of grain stability calculation is illustrated. From the tables, values for grain volume, VCG and VHMs are noted down. The mass of grain in each compartment is calculated by the formula,

The tabulated VHMs are multiplied by the appropriate correction factors to get the actual VHMs For holds 2, 3 and 4 no correction factor is necessary. Holds 1 and 5 are partly filled and the KG used is that of the actual grain cargo in the hold.  The correction factor used therefore is 1.12. Let’s say the total grain that is loaded is 19200m3.

Load displacement      = Lt Wt + Cargo + Bunkers + FW + Constant
= 5110 + 15000 + 1540 + 310 + 150 = 22110 t. 
The VHM for filled compartments = 2100m4, corrected VHM = 2100m4
The VHM for partly filled compartments = 3121m4, corrected VHM = 3121 x 1.12 = 3496m4.
Total VHM’s 5596 m4 Taking all the weights on board into account KG is found by moments. Let the solid KG be 7.931m

KG (fluid) = 7.931 + 0.042 = 7.973m.

KN values for various angles of heel and the ship’s loaded displacement are noted down from the KN tables. KM is found for the sailing draft. Let this be 8.8m. The curve of statical stability is plotted using appropriate scale.

The heeling arm curve is plotted by joining λ0 and λ40 points.

Where the heeling arm curve intersects the righting arm curve a vertical line is drawn till x axis to find the list angle for the assumed grain shift. This angle should be less than 12° or smaller angle applicable. In the present example this angle is 8°.

The residual area between the heeling arm and righting arm curve is to be calculated till the smaller of angle of flooding, maximum vertical separation and  40°. This area is to be not less than 0.075 mc. Let the angle of flooding at present draft be 38°.

The height of residual part at 23° and 38° from curve are  0.43m and 0.62m respectively.

This area is more than 0.075mc hence the condition satisfied.
The GM fluid is 8.8 – 7.973 = 0.863m.
The GM fluid as read from the curve is 0.85m, is almost the same as found from the graph.
The relevant condition satisfied The ship’s loaded condition complies with the minimum intact stability of the International Grain Code.

What are the contents of Grain Stability Booklet?
Information in printed booklet form shall be provided to enable the Master to ensure that the ship complies with this code when carrying grain in bulk on an international voyage. This information shall include that which is listed in regulation 6.2 and 6.3 of part A of code.

6.2 Information which shall be acceptable to the administration or to a contracting Government on behalf of the Administration shall include:

  1. Ship’s particulars
  2. Lightship displacement and the vertical distance from the intersection of the moulded base line and midship section to the centre of gravity (KG)
  3. Table of liquid free surface corrections
  4. Capacities and centres of gravity
  5. Curve or table of angle of flooding, where less than 400 at all permissible displacements. 
  6. Curve or tables of hydrostatic properties suitable for the range of operating drafts and
  7. Cross curves of stability which are sufficient for the purpose of the requirements in A7 and which include curve at 120 and 400.

6.3 Information which shall be approved by the administration or by a contracting Government on behalf of the Administration shall include:

  1. Curves or tables of volumes, vertical centres of volumes, and assumed volumetric healing moments for every compartment filled or partly filled or combination thereof including the effects of temporary fittings.
  2. Tables or curves of maximum permissible heeling moment for varying displacement and varying vertical centres of gravity to allo0w the master to demonstrate compliance with the requirement of A 7.1. This requirement shall apply only to ships the keels of which are laid on or after the entry into force of this code.
  3. Details of the scantling of any temporary fittings and where applicable the provisions necessary to meet the requirement s of A7, A8 and A9
  4. Loading instructions in the form of notes summarizing the requirements of this code.
  5. A worked example for the guidance of the master and
  6. Typical loading service departure and arrival conditions and where necessary intermediate worst service conditions.

What is the provision for carrying grain for a ship that is not provided with document of authorization?
Optical stability requirement for ship without document of authorization carrying partial cargoes of bulk grain:
A ship not having on board a document of authorization may be permitted to load bulk grain provided that:

  1. The total weight of the bulk grain shall not exceed one third of the deadweight of the ship.
  2. All filled compartment trimmed shall be fitted with centerline division extending for the full length of such compartments downwards from  the underside of the deck or hatch covers to a distance below the deck line of at least one eight of the maximum breath of the compartment or 2.4m, whichever is the greater expect that saucers duly constructed may be accepted in lieu of a centerline divisions in and beneath a hatchway except in the case of linseed and other seeds having similar properties.
  3. All hatches to filled compartments trimmed shall be closed and covers secured in place.
  4. All free grain surfaces in partly filled cargoes space shall be trimmed level and secured as provided in code.
  5. Throughout the voyage the metacentric height after correction for the free surface effects of liquids in tanks shall be 0.m or that given by the following formula whichever is the greater.

L = Total combined length of all full compartments (metres)
B = Moulded breadth of the vessel (Metres)
SF = Stowage factor (cubic metres per tonne)
Vd = Calculated average void depth calculated in accordance with B (Metres- Mote not millimeters).
D = Displacement (tones) and

6. The Master demonstrate to the satisfaction of the administration or the contracting Government of the port of loading on behalf of the Administration that the ship in its proposed loaded condition will comply with the requirements of this section.

What is saucer in context of Grain? What does saucer do? How is it created?
Saucer can be made in way of a hatch opening to reduce the healing moment, instead of a longitudinal division,  in case of a filled trimmed compartment. This however, can not be done in the case of linseed and other seed having similar properties. The depth of the saucer measured from the bottom of the saucer to the deck line shall be as follows:
1.   For ships with a moulded breadth of upto 9.1m not less than 1.2m
2.   For ships with a moulded breadth of 18.3m or more not less than 1.8m
3.   For ships with a moulded breadth between 9.1m and 18.3m the minimum depth of the saucer shall be calculated by interpolation.

The top of the saucer shall be formed by the underdeck structure in way of the hatchway i.e. hatch side girders or coming and hatch end beams. The saucer and hatchweay above shall be completely filled with bagged grain or other suitable cargo laid down on a separation cloth or its equivalent and stowed tightly against adjacent structure so as to have a bearing contact with such structure to a depth equal to or greater than one half of the depth of saucer. If hull structure to provide such bearing surface is not available. The saucer shall be fixed in position by steel wire rope, chain or double steel strapping and spaced not more than 2.4m apart.

What do you understand of Bundling in grain? How it is accomplished?
As an alternative to filling the saucer in a filled trimmed compartment with bagged grain or other suitable cargo a bundle of bulk grain may be used provided that : The dimensions and means for securing the bundle in place are the same as specified for a saucer.

  1. The saucer is lined with a material acceptable to the administration having a tensile strength of not less than 2,687N per 5cm strip and which is provided with suitable means for securing at top.

2. As an alternative to above a material acceptable to the Administration having a tensile strength of not less than 1.344N per 5cm strip may be used if the saucer is constructed as follows:
a. Athwartship lashing acceptable to the administration shall be placed inside the saucer formed in the bulk grain at intervals of not more than 2.4m. These lashings shall be of sufficient length to permit being drawn up tight and secured as the top of the saucer.
b. Dunnage not less than 25mm in thickness or other suitable material of equal strength and between 150mm and 300mm in width shall be placed fore and aft over these lashings to prevent the cutting or chafing of the material which shall be placed thereon to line the saucer.

3. The saucer shall be filled with bulk grain and secured at the top and further dunnage shall be laid on top after lapping the material before the saucer is secured by settings up the lashings.
4. If more than one sheet of material is used to line the saucer they shall be joined at the bottom either by sewing or by a double lap.
5. The top of the saucer shall be coincidental with the bottom of the beams when these are in place and suitable general cargo  or bulk grain may be placed between the beams on top of the saucers.

What preparation must be done on grain surface prior overstowing with bagged grain or other compatible cargo?
Overstowing

  • Where bagged grain or other suitable cargo is utilized for the purpose of securing “partly filled” compartments the free grain surface shall be level and shall be covered with a separation cloth or equivalent or by a suitable platform. Such platform shall consist of bearer spaced not more than 1.2m apart and 25mm boards laid thereon spaced not more than 100mm apart. Platforms may be constructed of other materials provided they are deemed by the administration to be equivalent.
  • The platform or separation cloth shall be topped off with bagged grain tightly stowed and extending to a height of not less than one sixteenth of the maximum breadth of the free grain surface or 1.2m whichever is the greater.
  • The bagged grain shall be carried in sound bags which shall be well filled and securely closed.
  • Instead of bagged grain, other suitable cargo tightly stowed and exerting at least the same pressure as bagged grain as above may be used.

How do you go about strapping of grain surface?
When in order to eliminate heeling moments in partly filled compartments, strapping or lashing is utilized, the securing shall be accomplished as follows

  1. The grain shall be trimmed and leveled to the extent that it is very slightly crowned and covered with burlap separation cloths, tarpaulins or the equivalent.
  2. The separation cloths and / or tarpaulins shall overlap by at least 1.8m.
  3. Two solid floors of rough 25mm by 150mm to 300mm lumber shall be laid with the top floor running longitudinally and nailed to an athwartships bottom floor.   Alternatively, one solid floor of 50mm lumber, running longitudinally and nailed over the top of a 50mm bottom bearer not less than 150mm wide, may be used. The bottom bearer shall extend the full breadth of the compartment and shall be spaced not more than 2.4m apart. Arrangement utilizing other materials and deemed by the administration to be equivalent to the foregoing may be accepted.
  4. Steel wire rope (19mm diameter or equivalent) double steel strapping (50mm × 1.3mm and having a breaking load of at least 49kN), or chain of equivalent, each of which shall be set tightly by means of a 32mm turnbuckle, may be used for lashings. A winch tightner used in conjunction with a locking arm may be substituted for the 32mm turnbuckle when steel strapping is used provided, suitable wrenches are available for setting up as necessary. When steel strapping is used, not less than three crimps seals shall be used for securing the ends. When wire is used not less than four clips shall be used for forming eyes in the lashings.   
  5. Prior to the completion of loading the lashing shall be positively attached to the framing at a point approximately 450mm below the anticipated final grain surface by means of wither a 25mm shackle or beam clamp of equivalent strength.
  6. The lashing shall be spaced not more than 2.4m apart and each shall be supported by a bearer nailed over the top of the force and aft floor. This bearer shall consist of lumber of not less than 25mm by 150mm or its equivalent and shall extend the full breadth of the compartment.
  7. During the voyage the strapping shall be regularly inspected and set up where necessary

How is the grain surface secured with wire mesh?
When in order to eliminate grain heeling moments in “partly filled” compartments, strapping or lashing is utilized the securing may as an alternative to the method described in A17, be accomplished as follows: 

  1. The grain shall be trimmed and leveled to the extent that it is very slightly crowned along the fore and aft centerline of the compartment.
  2. The entire surface of the grain shall be covered with burlap separation cloths, tarpaulins, or the equivalent. The covering material shall have a tensile strength of not less than 1.344N per 5cm strip.
  3. Two layers of wire reinforcement mesh shall be laid on top of the burlap or other covering. The bottom layer is to be laid athwartships and the top layer is to be laid longitudinally. The lengths of wire mesh are to be overlapped at least 75mm. The top layer of mesh is to be positioned over the bottom layer in such a manner that the squares formed by the alternate layers measure approximately 75mm by 75mm. The wire reinforcement mesh is the type used in reinforced concrete construction. It is fabricated of 3mm diameter steel wire having a breaking strength of not less than 52kN/cm2, welded in 150mm × 150mm square. Wire mesh having mill scale may be used but mesh having loose flaking rust may not be used.

4. The boundaries of the wire mesh at the port and starboard side of the compartment shall be retained by wood planks 150mm × 50mm.
5. Hold down lashings, running from side to side across the compartment, shall be spaced not more than 2.4m apart expect that the first and the last lashing shall not be more than 300mm from the forward or after bulk head, respectively. Prior to the completion of the loading each lashing shall be positively attached to the framing at the point approximately 450mm below the anticipated final grain surface by means of either a 25mm  or beam clamp of equivalent strength. The lashing shall be led from this point over the top of the boundary plank described in A 13.1.4, which has the function of distributing the downwards pressure exerted by the lashing. Two layer of 150mm × 25mm plank shall be laid athwartships centered beneath each lashing and extending the full breadth of the compartment.
6. The hold down lashing shall consists of steel wire rope (9mm diameter or equivalent), double steel strapping (50mm × 1.3mm and having a breaking load of at least 49kN), or chain of equivalent strength, each of which shall be set tight by means of a 32mm turnbuckle. A winch tightener, used in conjunction with a locking arm, may be substituted wrenches are available for setting up as necessary. When steel strapping is used, not less than three crimps seals shall be used for securing the ends. When wire rope is used, not less than four clips shall be used for forming eyes in the lashings.
7. During the voyage the hold down lashings shall be regularly inspected and set up where necessary.

(You may also visit my youtube videos @captsschaudhari.com)
Link: https://www.youtube.com/channel/UCYh54wYJs1URS9X5FBgpRaw/feature

neha10041987

Leave a Reply

%d bloggers like this: