Spiral weld

FIG. 10-164 Longitudinal and spiral-weld joint factor E. NOTE It is not permitted to increase tlie joint quality factor by additional examination for joints 1, 2, and 4a. (EjLtracted from ANSI B31.3—19S0, with petmission of the publisher, theAmetican Society of Mechanical Engineets, New York.)... 

Figure 7.86 Cross-section through SOHIC in spiral-welded linepipe (Courtesy of Malcolm Hay)...

The process for manufacturing helical seam line pipe (previously called spiral weld) is shown schematically in Figure 5.9. As in ERW pipe, steel strip in coil form is used, but the coil is formed into a spiral. The seams are welded by the DSAW process as in UOE pipe. Some early prejudice against helical... 

Spiral weld pipe is made from strip in coil form. After the strip is uncoiled, it proceeds to a trimmer and then to forming rolls that shape it into spiral form. The spiral seam is submerged arc welded automatically and continuously—first on the... 

A Longitudinal or spiral welds in the main shell, necks or nozzles, or circumferential welds connecting hemispherical heads to the main shell, necks, or nozzles ... 

Spiral butt welded pipe is being increasingly used in Europe. This product must not be confused with spiral welded pipe to ASTM A211, which may be lap or lock-seam jointed. The European material... 

It is always worth while to pay attention to the quality of welded pipe by quoting the correct specification and by adequate shop inspection. API 5L and ASTM A155 require electric fusion welds to be double side welds, as do DIN 1626 Blatt 3 and Blatt 4 and BS 3601 SFW (spiral weld). ASTM A134, DIN 1626 Blatt 1 and Blatt 2 and BS 3601 EFW, on the other hand, permit single side welds. The quality control measures called for in the specifications permitting single side welds do not guarantee freedom from defects, so they are not suitable for the more severe duties. 

Examples of SOHIC failure in spiral-welded line pipe are common forms of failures. Failures were also encountered in electric-resistant welded pipes because of HIC. Failures of seamless line pipes have also been reported (30). HIC-related damage and failures of 20 line pipes in H2S and CO2 atmospheres have been reported (19). Despite the availability of adequately HIC-resistant line pipe since the late 1970s, failures are still occurring in pipelines constructed since then. 

FIGURE 20.43 Hydrogen-induced crack formation in a spiral-welded natural gas pipeline (St. 52.3) caused by condensate containing H2S and CO2. 

Spiral weld A weld joint having a helical seam. 

The plywall system is a combination of multilayer- and coillayer-cons-truction. The shell segments are spirally welded by three-plate welding with the layer below. 

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