Guidelines for storing, handling and transporting completion tubing

1 Storage

The design of pipe racks depends on local conditions (load capacity, degree of permanency, etc). Racks can be made with pipe supports (stringers) set on concrete or wooden bases. Drilltec aluminium racks should be considered for certain tubulars such as CRAs (Corrosion Resistant Alloys). Spacing should be around 2 m which allows 20 ft joints to be stored on two stringers and 40 ft joints on four stringers.

Tubing should be stacked with separators between layers. Separators in the layers should be vertically aligned to avoid bending of the pipes. Timber (with a wedge at both ends) of around 10 cm can be used as separators. Fresh timber should be avoided as the moisture squeezed out can cause corrosion and pitting of the tubing in contact with the separators.

For drainage in wet climates, it is recommended to separate the joints with a wedge or T. The racks should be tilted towards the pin-end and the pipe fitted with open-ended protectors.

For space requirements, the following points should be considered:

• height of stack;
• diameter of tubing (including coupling);
• range of tubing and total footage;
• size of pipe racks; 
• working space.

In accordance with API RP 5C1, the height of the stack should not exceed 10 ft (3 m) including the pipe rack. For small quantities, particularly small diameter tubing, it is impractical to build a stack to the maximum height. The height must be reduced and the width increased in proportion. (A rough guide is that the height of tubulars in a stack should not exceed the base width). Therefore when planning pipe racks, allowance must be made for small quantities which require more space than the API table indicates.

The length of each pipe rack should be sufficient to accommodate Range 3 tubulars.

A lane not less than 20 ft (6 m) wide should be allowed on either side of the racks for transport and handling operations, with a space of approximately 5 ft (1.5 m) between racks.

·The tubing should not be stacked directly on the ground, the first tier should be at least 50 cm from the ground.

·Metal-to-metal contact should be avoided, this includes supports and other joints of tubing. Plastic separators and chocks are preferred as the moisture within wood (which may have been treated with chemicals such as chlorine) will cause local corrosion, especially where CRA pipe is being stored.

·Thread protection should always be fitted to protect the threads from impact and corrosion damage, and the tubing racked with at least 5 cm (2 in) between the tubing ends to allow the threads to be cleaned/inspected.

·A maximum stacking height must be maintained, e.g. 5 tiers for 41/2" tubing.

1.1 Storage administration

Tubing and casing should be stored according to size and grade. Electronic tagging will aid in this respect and will facilitate the central filing of the steel mill certification and pipe inspection reports.

Outside storage of CRAs in coastal regions for more than four months is not recommended.

API coding specified in API 5CT relates to the 4 categories of tubing, listed below:

• Group 1: All tubing in grades H, J, K and N, e.g. H40, J55, K55 and N80.
• Group 2: All restricted yield strength tubing in grades C and L, e.g. C75, C75 13 Cr, C90, C95 and L80.
• Group 3: All high grade tubing in grade P, e.g. P105 and P110.
• Group 4: All special service tubing in grade Q and/or wall thicknesses agreed upon between the purchaser and manufacturer, e.g. Q125.

Groups 1, 3 and 4. Each length of tubing should be colour coded by a paint band or bands encircling the pipe at a distance no greater than 0.6 m (2 ft) from the tubing coupling or box, or on the collar itself.

• H-40 None
• J-55 One bright green band
• K-55 Two bright green bands
• N-80 One red band
• P-105/110 One white band
• Q-125 One orange band

Group 2. Each length of tubing is colour coded by one of the following methods:

• paint band or bands encircling the pipe as for the previous grades;
• paint band or bands encircling the centre of the coupling; 
• painting the entire surface of the coupling.

If the entire surface of the coupling is painted, it will be with the first stated colour, i.e L-80 will be painted red with brown bands.

2 Thread protectors

There are two types of thread protectors:

2.1 Threaded protector (for transit)

They are used from the mill to the well location, where they are taken off for removal of the storage compound. These are composed of a moulded polymer body reinforced with a cylindrical steel insert; some makes may consist of only polymer. Metal protectors should not be used.

Transit protectors can protect only individual tubing during movement. Protection is not guaranteed when joints are bundled together, since the impact on one protruding joint will be much greater.

Thread protectors with a threaded metal interface are not recommended, especially for CRA tubulars.

2.2 Non-threaded protector (for handling)

They are installed on the pin prior to lifting the tubulars to the drill floor. In most cases it is either clamp-on or an inflatable type.

Clamp-on style protectors designed for API connections can cause seal damage when used for premium connections. The operating mechanism can contribute to seal area damage if the protector is incorrectly installed.

The Klepo inflatable protector is a solid polyurethane circular ring inflated by the rig air supply once it has been installed over the pin end threads. This provides a uniform 360° grip and is independent of thread type. Once the joint is ready for stabbing it is deflated and removed.

2.3 Performance criteria

·Impact resistace / ·Protection against water penetration / ·Resilience to thread stripping / ·Resistance to vibrational loading / ·Chemical resistance / ·Weathering resistance

Thread profile basic functions:

-primary barrier to moisture, storage grease is considered an additional secondary barrier; / a locking fit between the protector and pipe; / a threaded profile along the length of the pipe threads; / the pitch, taper and diameter should correspond within reasonable limits to those of the pipe / the protector should protect the seal from the inside.

3 Preservation

The usual contaminants are the result of domestic and industrial combustion and when close to the sea, wind borne salt. The most expensive method of preservation is not necessarily the most suitable.

3.1 Pipe body

Unless otherwise requested, tubing is ordered in accordance with API Specification 5CT and therefore the pipe body will have a mill coating. The purpose of the mill coating is to protect the tubulars from rusting in transit. Since API is not specific in this respect, the type and quality of these coatings vary as does the length of time the coatings give protection in storage. If the tubulars are to remain in storage for a long period, the mill coating could be supplemented or completely cleaned and re-coated.

Whenever grit blasting is carried out to clean the tubing, extreme care should be taken to ensure that the proper thread protectors are fitted to prevent damage .

Where an internal surface coating is required, the use of coatings which give a thick film should be avoided because of potential problems running wireline tools.

Particular care is required to prevent the corrosion of notch-sensitive tubulars such as C95 and P110. If storage for more than three to four months is foreseen, unless adequately coated when delivered, these grades should be cleaned and coated internally and externally.

As already mentioned, thorough cleaning is essential for effective conservation and all scale, rust, dirt, oil and grease should be removed before any coating is applied. If any deposits on or in the tubulars have contained salts, such as from sea water spray during shipment, the surfaces should be washed with fresh water and then dried.

3.1.1 Pipe body storage compound

·Internal:

• Blacksmith CP 914
• Agma Synergen 718

External:

• Agma Synergen 501 
• Shell Ensis HP

Several external coatings have been identified as only acceptable if the tubulars are covered (e.g. with a tarpaulin). These are:

• Malacote 400;
• Oil Centre Research Inc. 911
• Shell Ensis MD.

Threaded connections storage compound

Recommended storage compounds for thread corrosion protection are given below. Whilst in storage, thread protectors should be removed from time to time (two monthly random stock inspection) to check that the thread compound is in good condition. If in doubt, washing, brushing and re-application of the compound should be carried out.

• Shell Rhodina Grease 2
• Geveko Mercasol 630
• Jet Marine Imperator 1078
• Kendex OCTG corrosion inhibitor
• TSC thread storage compound
• Cortec VC1-369
• Rust Vetco heavy /·RD5

The above storage compounds are not to be used as a running compound.

There are, however hybrid compounds available which can be used for both storage and running. These include:

• Kendex Enviro Seal
• Geveko Mercasol 633 SR Multimake White
• Cats Paw black 712 S
• Bestolife copperfree PTC
• Bestolife 2000 5% copper
• Shell Française SF 3646
• Showa Shell Type 3

4 Transport

Pipe should be externally and internally cleaned before dispatching to the rig site, preferably by water jet blasting.

Pipe should be drifted from the box end to pin end with a suitable 42" long (tubing size) API drift. Metal drifts should not be used. The threads should then be cleaned and inspected.

Extreme care should be taken when lifting pipe:

• when lifting by crane only slings or straps should be used (non-metallic on CRAs). Insertion of hooks into the pipe ends should not be allowed;
• when using a forklift the forks should preferably be padded to prevent damage;
• pipes should not be allowed to collide with each other.

4.1 Road

Always ensure that tubular goods are adequately secured, irrespective of how short the journey may be.

Forces are generated on the load when a vehicle brakes, accelerates, changes direction or crosses road undulations. These forces are frequently greater than the frictional restraint between load and platform which means that all loads must be secured by a restraining device. The device must be sufficient to withstand a force equal to not less than the total weight of the load forward and half of the weight of the load backwards and sideways.

The design and construction of anchorage points through which the securing device can be attached must allow twice the specified capacity acting in any direction. Anchorage points must be firmly attached to the chassis or to a metal cross member or outrigger and where practical with doubling plates.

Prior to moving off with the loaded vehicle all tensioning devices should be checked by the driver and after a few miles the lashings should again be checked, thereafter at regular intervals during the journey.

Onshore it is preferable for the tubulars to be handled separately rather than in bundles.

4.2 Water

The stowage and transportation of tubulars by marine craft will be the sole responsibility of the Master.

It is good operating practice to ensure that tubulars, where possible, be bundled in preparation for handling offshore. When bundled the slings are doubled wrapped and secured with a bulldog grip and a plastic tie-wrap. The bulldog stops the loops of the sling round the bundle from becoming loose during transit, the tie-wrap is an extra precaution to stop the bulldog from slipping.

The reason why the joints are bundled in this way is in case there is a snatch-lift (i.e. while the load is being unloaded from the vessel, the vessel heaves and dips due to wave action suddenly leaving the load supported by the crane) the load will be secure and joints will not become loose and fall.

It is important to ensure that the bundle is correctly balanced for each lift.

4.3 Low-temperature environments

Low ambient temperatures substantially reduce the size of the flaw necessary to cause failure. The following procedures, while being applicable in all circumstances, are particularly important for low temperature environments:

• Do not drop, bend, or scratch the pipe. If lengths of pipe have to be forcibly separated due to ice accumulation, take care not to scar the metal surface.
• Thread protectors should be removed without hammering or shock loading.
• Extra precautions should be taken when stabbing the pipe, since low temperatures reduce the impact resistance of the metal.
• Box and pin should be of equal temperature to ensure proper make-up. Use Arctic grade thread lubricant.

FRP are particularly sensitive to cold climates and require additional care.

5 Storage at wellsite

Tubulars should be handled and stored in the manner as discussed above.

Offshore, CRAs should be washed down with fresh water (not brine/sea water) to wash off salt which may have accumulated during the boat journey offshore. This process should be repeated regularly (i.e. every 7 days) until run.