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SRJ Snap Ring Joint

The dense network of piping on board a tanker or an FPSO is subject to vibration and corrosion damage. So maintenance is a crucial element in ship management and operation.

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Sectors

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  • OVERVIEW
  • VESSEL PIPEWORK

OVERVIEW

The Snap Ring Joint is currently undergoing a stringent test regime in order to gain Lloyds Register and ABS Type Approval for use in a variety of applications requiring high pressure fluid transmission and has patent protection in over seventy countries worldwide. Its pressure-withstanding ability has been successfully tested to 16,000 psi.

The SRJ provides a highly cost-effective alternative to welded joints in many applications in the piping system of a vessel. It removes the need for permit-to- work systems and the shutdowns required for hot works in hazardous areas. It eliminates the need to weld in the confined space and restrictive atmosphere in places such as double bottom ballast tanks.

The SRJ meets the need to minimise weight and bulk on board a vessel and compares favourably in this respect to conventional jointing methods in pipework. Weighing 60% less than a comparable flange, the SRJ imparts lower inertia loads on pressure vessels.

VESSEL PIPEWORK

Welding on board a vessel presents particular challenges in addition to the use of bulky equipment, the need for weld procedures, welder qualifications and non-destructive testing (NDT), further increasing the time devoted to maintenance operations.

The need to conduct repairs in hazardous and inaccessible areas is inevitable, but ensuring a gas-free atmosphere to permit welding is a major undertaking. Gas pockets in particular are a problem in areas such as the pump rooms of an oil tanker.

When pipes are subject to vibration, this is a particular problem for bolted flanges, since the bolts can be loosened and must undergo regular torsion tests to avoid failure. Furthermore, their mass is a serious impediment in a context where minimizing weight is critical.

The SRJ eliminates the need for welded repairs in piping systems and its installation is about five times faster and about 20% cheaper than conventional jointing methods, with trained fitters employed to prepare and machine the pipes on site, install the sleeve, place the clamp joint in position and install the shear wires.

The SRJ weighs 60% less than comparable flange joints. A 4" 900# flange for use on 4" Sch. 40 pipe for example, would weigh 50 kg, whereas a 4" SRJ weighs just 16 kg. The lower weight and volume of the SRJ compared with a flange allows for smaller pipe racks. The consequent weight and space-saving on a FPSO topside module can result in substantial cost savings. The reduced weight also means that the SRJ imparts lower inertia loads on pressure vessels.

During the process of achieving Lloyds Register and ABS Type Approval, the SRJ's ability to handle high-pressure fluid transmission has been successfully tested to 16,000 psi. Based on IACs standards, the SRJ coupling complies with the European Pressure Equipment Directive (PED).

Operating Principle and Key Features

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To install the connector (supplied pre-fitted with radial seals), the pipe ends are cut and prepared with the use of a conventional clamshell cutting machine. This machine, fitted with form tools, is used to machine the grooves required to locate the connector’s retaining wires in the pipe periphery.

If access is available at the pipe ends and one of the pipes can be moved longitudinally, then the SRJ connector would be installed onto one of the pipes to half its ength and the mating pipe is then pulled into the connector.

If however, the pipes cannot be pulled longitudinally, i.e. a spooled installation between two fixed ends, the connector would be completely assembled onto one of the pipes. This would leave its outer end flush with the pipe end. Then the mating pipe would be lowered into position and when the pipe ends are butted, then then the connector is centralised.

For larger OD connectors, a hydraulically-activated unit is used to position the connector on the pipe, thereby eliminating seal friction.

Alternatively, normal manual pipe handling equipment can be used. In all cases, once in position, the SRJ connector is locked in place by fitting the retaining wires. Typically, the overall length of the SRJconnector is equal to twice the pipe’s OD, so the actual access requirements are kept to a minimum, making its use ideal in tight access situations, such as the hook up phase of a project.

 

Nominal Pipe Diameter Pipe OD SRJ Diameter
4”
101.6mm
4.5”
114.3 mm
8”
203.2 mm
8.625”
219.075 mm
12”
304.8 mm
12.75”
323.85 mm

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Benefits & Advantages

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Benefits

Safety
  • Cold work installation – eliminates the risk associated with Welding.
  • Reduces risk of fugitive emissions
Size / Weight
  • 40/50% more compact than a comparable flange. Closer pipe runs.
Speed of Installation
  • approx 3 hours per coupling with less skilled technicians.
Cost Reduction
  • Time savings 18/24 hours per connection compared to welded flange.

Advantages

The SRJ offers many benefits over other pipe connection methods: –
  • Withstands high internal pressures and has equivalent mechanical strength of a weld
  • Eliminates costly welding workscopes by replacing coded welders with trained operatives
  • Speed of installation compared to welding workscope
  • Enhances safety on-site and ATEX requirements by eliminating the risks of welding
  • Does not compromise internal pipe coating, unlike welding
  • Avoids the need to weld difficult materials such as CuNi, Monel and Duplex
  • Potential for testing post-installation with the SRJ equipped with integrity ports
  • Lightweight and compact, cutting transport costs and enabling closer pipe rack design
  • Can be dismantled and reassembled

Installation Times vs. Welding

PROCESS
10” 900Lb
SRJ
Pipe Cutting and Preparation
=
=
Pipe Alignment
=
=
Flange alignment and welding per flange
10.1
N/A
Pre Heat
2.7
N/A
Stress relieve
5.9
N/A
XRay
1.73
N/A
Coupling Installation
N/A
3
Connecting flanges / gaskets / bolts
3.7
N/A
Total Hours
24.13
3
SRJ Saving
21.13

Note – Pipe preparation times for SRJ and welding considered to be equal.

SRJ vs. ANSI Flanges

Nominal Pipe Diameter Pipe O/D
SRJ Diameter
ANSI 900 LB Dia
4"
6.4"
11.5"
8"
10.7"
15"
12"
15"
24"
Nominal Pipe Diameter Pipe O/D
SRJ Weight
ANSI 900 LB Dia
4"
35 lbs
125 lbs
8"
175 lbs
415 lbs
12"
480 lbs
767 lbs

Snap Ring Joint Limited, 9 The Esplanade, St.Helier, Jersey, JE2 3QA, UK.
tel: 44 (0) 1534 626 818
e-mail: info@srj-technologies.com
Snap Ring Joint Limited. All rights reserved