ECA vs Batelle Fracture Control

[Essex57]

If a series of out of spec welds are suspected on a pipeline (e.g. the welds have not been to DnV spec), what is the best method to assess whether they are fit for service. ECA or Batelle?

 

[grampi1]

CTOD or J integral testing is the standard for girth weld ECA in all codes. US Codes would be API 1104 and API 579. Brittish have an eqivalent to API 579 but I don't recall the number. Reference to Battelle does not make much sense. Usually this refers to a Drop Weight Tear Test under B31.8 and API 5L which is a pipe body test and not appropriate for girth welds.

 

[SJones]

In what way were the welds "out of spec"?

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[Essex57]

Girth weld issues

I understood that the Battelle fracture model predicts the toughness required to prevent fracture initiation in the girth weld.

The pipe has fracture arrest properties based on DNV linepipe requirements, so the girth weld only requires toughness to prevent fracture initiation.

DNV requires matching arrest properties in the girth weld to that of the pipe body. This is considered by some to be conservative

Analyzing CVN values based on requirements to prevent fracture initiation in the weld metal requires only a fraction of the toughness in the girth weld as compared to the pipe body.

Therefore wouldn't the Battelle fracture control method for gas pipelines be a good basis for setting gas pipeline toughness requirements for both the girth weld and pipe body