P&I 钢管甲板货-GUIDLINES ON STOWAGE AND SECURING-1

Characteristics of Pipes

The characteristics of pipes which need to be borne in mind when planning their stowage and securing are as follows

1. pipes are relatively light;

2. pipes are round and may roll;

3. pipes have a low coefficient of friction;

4. pipes are hallow.

The first characteristic has a marked effect on the stability of the vessel and that in turn affects the transverse forces which act on the deck stowage when the vessel rolls in the seaway. When logs are carried both on and under deck, the resultant metacentric height (GM) is likely to be small and close to the lower limit. However, when pipis are stowed on deck and other, perhaps heavy, cargo - such as steel procucts - is stowed under-deck, this might give the vissel a large GM and a short roll period.

A stowage of pipes should be fo single size and type of pipes, the same diameter, length and finish, so as to produce a uniform block. If different sizes of pipe or with different coatings or end finishs are stowed together, the block will not be uniform, damage to the pipes may result and securing difficulties will be encountered.

The pipes must be provided with adequate and suitable dunnaging and packing materials to support and chock the pipes in the stowage, to increase the coefficient of friction where possible and to protect the ends and surfaces against damage resulting from abrasion between adjacent pipes and between securing arrangements and the pipes.

During the voyage, if seas are shipped on deck, sea water may collect in the pipes, particularly those in stowages further forward, and the weight of that water will further increase the transverse forces and loadings on the securing arrangements. This should be borne in mind during the voyage and particularly when adverse condition are forecast.

Fig. 2. Pipe surfaces should be protected from securing devices by suitable dunnaging and packing materials.

The following warning given in the Timber Deck Cargo Code should always be remembered.

Warning

The lashings are not designed to provide a means of securing against imprudent ship handling in heavy weather.

BEFORE LOADING BEGINS

Before the stevedores can begin loading pipes, calculations must be carried out to determine how many pipes are to be loaded on top of the hatch covers and in how many tiers. The size - lenght, breadth and height - of the stowage can then be determined. Also, and of great importance, the weight of the stowage can be calculated.

The weight of the stowage - both in terms of the total weitht of the stowage on the hatch covers and the tonnage per square metre- must not exceed the maximum permissible loading of the hatch cover. Sufficient load-spreading timber dunnage should be used appropriately to ensure the weitht of the cargo is satisfactorily spread (Fig. 3).

Calculations should therefore be carried out in advance to ensure that there will be no overloading of the hatch covers, and to ensure that sufficient timber dunnage will be available for the construction of the stowage. Also, calculations for the necessary securing arrangements must be done to ensure that sufficient lashing material are available to secure the stowage.

Fig. 3 Timber dunnage should be used to spread the load on hatch covers.

STOWAGE OF PIPES

Pipes should be stowed as follows.

Advice for stowing pipes on deck

1. Pipes should be stowed in the fore-and-aft line of the vessel on lines of soft timber dunnage laid athwartships on the hatch top, preferably laid above hatch-cover transverse stiffening members.

2. Each pipe should be stowed hard up against the adjacent pipe and wedges should be inserted against the inboard and outboard bilge of each pipe, and nailed to the base timbers, to prevent rolling (Fig.4).

3. Second-tier and third-tier pipes, if carried should be stowed in the cantlines of the pipes in the tier below with friction-increasing material, preferably rubber matting, fitted between each successive tier.

4. Suitable packing material (timber, rubber matting, etc.) should be fitted in way of alll securing arrangements at points of contact to minimise abrasion damage.

5. The block stowage of pipes may be considered to be a single unit for securing purposes, provided it is a well-formed, tight stowage. Calculations should be completed to determine the strrength of the securing arrangements that are required to prevent transverse and longitudinal sliding. Transvese tipping is considered not to be a problem.

   

   Fig.4 Timber wedges nailed to base timbers are required along both sides of every pipe to prevent rolling.