Gas Technology Institute
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Burnthrough Limits for In-Service Welding

SKU: GRI-04/0135
Burnthrough Limits for In-Service Welding

The objective of this project was to further investigate the lower limit of pipe wall thickness and to further investigate the effect of welding parameters and pipeline operating conditions, including pressure, on the occurrence of burnthrough when welding onto thin-wall in-service pipelines.
Document Type
Report
Report Type
Final Report
Corporate Source
Edison Welding Institute, Columbus, OH
Sponsor
Gas Research Institute, Des Plaines, IL
Pagination
153p
Product Media
PDF Download
$295.00 / Each
 
Availability: In Stock
Summary:
The objective of this project was to further investigate the lower limit of pipe wall thickness and to further investigate the effect of welding parameters and pipeline operating conditions, including pressure, on the occurrence of burnthrough when welding onto thin-wall in-service pipelines. An initial series of experiments was conducted in thin wall pipe (0.125 to 0.188 in.) to investigate the effect of pressure and welding direction on the risk of burnthrough. A second series of experiments investigated the effect of other welding variables, including electrode angle, electrode polarity, and welding against the edge of a full-encirclement sleeve. The third series of experiments concentrated on developing limits for welding onto in-service pipelines thinner than 0.125 in. (3.2 mm). The results indicate that pressure does have an effect on the ability to make safe welds on thin-wall pipe, but only at heat input levels well in excess of those predicted by thermal analysis modeling. Unsafe welds made in the longitudinal direction tended to contain weld centerline cracks; whereas, unsafe welds made in the circumferential direction tended to exhibit excessive bulging and traditional puncture-type burnthroughs. Results also indicate that it is possible to weld onto an in-service pipeline with a wall thickness down to 0.109 in. (2.8 mm) provided that current level is restricted and heat input limits are observed.
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