CHALLENGES

When carrying out repairs or retrofi ts on the pipework of FPSO topside modules, workscopes must be carried out quickly and safely, given that the FPSO will be on-station and in operation. They must cause minimal disruption to operations, production and storage capacity. Welding operations involve all the constraints of doing hot works in a hazardous area, with hot work permits and the need to comply with ATEX regulations for equipment protection and setting up safe areas for welding. This is also in addition to the inherent

shortcomings of welding, such as the need for coded welders, weld qualifi cations, prepping and NDT.The weight of the topside structure and its interaction with the hull of the FPSO is a vital consideration and has a major impact on the hull’s strength and fatigue life.So in the context of a topside layout, which can feature up to 15 independent single deck and double-deck modules with weights ranging from 1000 – 3000 tonnes, the weight of pipeline fi ttings is a key factor.

The processing modules of an FPSO are designed according to the size of the vessel and this determines the space

available for pipe racking. Since space is at a premium, the volume of pipework components must be kept to a minimum, with adequate clearance requirements under the modules for non-destructive and visual examination, and maintenance.

Vibration is an issue in topside modules, notably with refurbished pumps on FPSOs and it may travel considerable distances through pipework downstream. This leads to problems for bolted fl ange connections, where the bolts may loosen and result in leakage.

SRJ APPLICATIONSFOR FPSO MODULES

SOLUTION

The Snap Ring Joint (SRJ) is an innovative new pipeline coupling technology designed to respond to the shortcomings of welded joints and traditional mechanical connectors. It eliminates the need for welded repairs in pipework. Two shear rings, of counter-wound wire - each of which fi lls a groove in the pipe OD - hold the SRJ coupling and pipe together. The coupling wall thickness acts as a supporting sleeve which compensates for the grooves in the pipe OD. This circlip technology increases the strength of the wire connection by 3.14 x diameter (shear strength). The SRJ also features an internal double isolation sealing mechanism of two elastomeric radial seals and a face-to-face seal to ensure tightness, and to eliminate the risk of leakage.

Installation of the SRJ is much faster and considerably cheaper than conventional jointing methods, with trained operatives used to prepare and machine the pipes on site, install the sleeve, place the joint in position and install the wires. Use of the SRJ can play a signifi cant part in reducing topside module mass, thereby curbing the need for deck plating inserts and under deck reinforcement, since it weighs considerably less than

comparable fl ange joints. A 4” standard 600 # RF fl ange weighs 32 kg, compared to the equivalent SRJ fi tting which weighs just 17 kg. The reduced weight also means that the SRJ imparts lower inertia loads on pressure vessels.

The lower volume of the SRJ compared with the fl ange makes it particularly apt for use in areas where there is signifi cant congestion (pipework and equipment) and confi nement due to structures such as vents.This e� ectively allows the creation of more processing space, so the size of the crackers and convertors on board the FPSO can be increased. It also ensures that pipework is easier to inspect and maintain. If a welded joint is in a location where it is particularly subject to vibration damage, then its replacement with an SRJ will provide a connection strength which is equal to twice the strength of the pipe itself. The SRJ also provides a neat solution to the problem of bolted fl anges which often fail due to excessive vibration.

Whilst ferrous materials are widely used, the SRJ can be designed to match the material specifi cations of any pipework to be joined. No pipe specifi cation or schedule changes are needed and even corrosion allowances are

calculated in the same manner. The SRJ is capable of handling any corrosive fl uids that the pipeline is designed to carry, such as waters, oils, gases, CO2 and H2S. Its use results in less internal corrosion than with welded joints, since FBE lined pipe can be butted up in the SRJ coupling, minimising

exposure of the steel pipe to corrosive fl uids.

Designed to withstand temperatures ranging from -29C to 150C, the SRJ has been extensively tested during the Lloyds Register certifi cation process and the 8” fi tting held pressure of more than 16,000 psi (over 1,000 atm) with no e� ect on the integrity of the joint.

Following a highly stringent test regime, the SRJ has gained Lloyds Register Type Approval for use in a variety of applications requiring high pressure fl uid transmission in shipping, onshore pipelines, o� shore topside applications and facilities. The technology has received patent protection in over 70 countries worldwide.

info@srj-technologies.com +44 1534 626 818

The SRJ is an innovative new pipeline coupling technology designed

to eliminate the need for welded

repairs in pipework