Lokring fittings are a mechanical weld equivalent pipe solution. Fittings are rapid to install and are qualified to ASME B31.1 and B31.3, as well as Lloyds Type Approval. It is a proven solution within the process industry and provides significant reductions in total installation costs.
The fittings use a patented technology to connect piping and tubing of up to
3 inches in diameter. They are designed to be used for field fabrication, rapid repair, installation in tight access areas, and tie-ins of shop fabricated piping.
Fittings are installed with simple hydraulic tooling to form a leak-tight, metal-to-metal seal without O-rings or other elastomeric seals. The fittings are installed without hot work or open flame, making them ideal for installations in operating areas where welding is not feasible due to explosive atmospheres. Because no hot work permit is required, the installation of Lokring fittings is safe.
The Lokring 333
Lokring 333 Process Fittings have been designed as a low alloy carbon steel solution for sour gas service applications. The fittings are made out of NACE compliant fitting material – AISA 4130 NACE grade carbon steel – and have been tested to NACE TMO-177
Method A. The product has been designed with a corrosion allowance of 3.2 mm.
The fittings can be used on A333 low temperature carbon steel piping, and are charpy impact tested to -46º Celsius, with a minimum shear of 85 per cent.
Following extensive ASME Qualification – including flexural fatigue, burst, tensile and torsion testing – Lokring have pipe couplings now available from half an inch to 2 inches, and with weld-free ANSI flanges in production. The couplings are qualified for use on A333, A106, API5L Grade B & A53 pipe – schedule 40, 80 and 160.
The fittings will meet the criteria of NACE MRO175/ISO15156 and MR0103-2007 for refineries. The fitting material specification meets AISI/SAE 4130 (UNS G 41300) Low Alloy NACE Grade Carbon Steel Fittings, and have Blue Zinc Chromate plating to ASTM B633.
Elastic strain preload (ESP) technology
During installation, the axial movement of the Lokring driver over the fitting body swages the body onto the pipe surface, compressing the pipe wall first elastically and then plastically. The pipe wall resists this swaging action, generating high unit compressive loads at the contact points between narrow sealing lands inside the fitting body and the pipe surface.
These contact stresses are sufficiently high to plastically yield the pipe surface under the multiple sealing lands, forming a 360 degree circumferential, permanent, metal-to-metal seal between the pipe and fitting body. The driver, which experiences a small increase in diameter (elastic strain) during installation, exerts an elastic, radial pre-load on the metallic seals for the life of the connection.
Lokring has been trialled and proven over many years, and are now incorporated in many companies’ piping specifications. Clients consistently advise of cost savings of 40-50 per cent compared with the alternative of welding and hot work.
Heath Pipeline Services is the Australian distributor for Lokring products. For more information contact Geoff Gardiner on g.gardiner@heathservices.com.au or visit www.heathservices.com.au