Reasons for cracking of stainless steel flanges
1) Physical and chemical analysis
First, the chemical composition of the stainless steel flange is analyzed, and the analysis results show that the chemical composition of the flange and the welding material meet the requirements of the relevant standards. The Brinell hardness test was performed on the outer surface of the flange neck and the sealing surface, and the Brinell hardness test value met the requirements of JB4728-2000 standard. Under the premise that the chemical composition of the material is qualified, the hardness test is qualified, the pipeline installation meets the technical requirements, and meets the operational specification of the pressure test, cracks will appear in the pipeline flange during the pressure test process, which indicates the defect depends with the internal structure of the flange or other unknown factors.
flanges
2) Analysis of crack properties
The leaking flange was disconnected from the pipeline and a full macro inspection was carried out. Cracks were found on the inner surface of the flange with a maximum length of 3 mm and a width of 0.5 mm. The cracks and their surroundings produced rust spots, which were also found on the inner surface of the flange bolt holes. More cracks were found and many non-metallic inclusions were found on the sealing surface of flanges and other places. Some non-metallic inclusions formed small indentations on the surface of the gasket surface
Wilson Pipeline is a leading manufacturer and distributor of flange fittings material from alloy steel stainless steel to carbon steel.products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings. ASME B16.5 ASME B16.9 ASME B16.11 EN1092,ANSI ASTM,GOST,JIS,DINWilson Pipeline products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.If you want to have more information you want to share your enquiry with us, contact us at sales@wilsonpipeline.com