API 1104 minimum weld reinforcement (cap height)

[NDTWizard]

The 20th edition of API 1104 does not specify minimum cap height, bot it can be implied by the illustrations, and sample welding procedure forms that a minimum cap height is expected. Does anyone know what the minimum recommended cap height should be, and if "low cap" can be called for repair by a radiographer?

 

[SectionIX]

It does, actually, list the minimum cap height.

Clause 7.8.2 states "At no point shall the crown surface fall below the outside surface of
the pipe, nor should it be raised above the parent metal by more than 1/16 in. (1.6 mm)."

Low cap can be called:

A. If the above clause is not met.
B. As shown in a customer specification that complies with 7.8.2.


Also note that the phrase 'nor should it be raised above the parent metal by more than 1/16 in. (1.6 mm)' is a recommended practice and not a requirement. I've seen company specifications limit cap height to 0.100" or 0.125" for fatigue purposes.

 

[NDTWizard]

Thanks to the person who replied about cap height.

Do you know if API 1104 anywhere addresses the issue of excess penetration of the root? I have recently seen welds with welding wire and even electrodes protruding through into the pipe.
I have not been able to find anywhere where this is identified as a problem.

 

[SectionIX]

API 1104 does not address excessive root penetration per se, except for related conditions such as meeting density requirements of Clause 11.1.10.1 of this document. IQI Wire wire identification may also be hampered by excessive root penetration.

As far as all comments are concerned, clause 11.1.7 does give the company the final right of acceptance or rejection.

Welding wire and electrodes stickout could be a problem for pigging operations and are often found in downstream traps.

Futher guidance maybe found in other specification/codes relevant to your situation.


Corporate specifications are the best way to address all issues described above.