Cut out of welding due to Repair 1

[petro84]

Hi Dear Friends
It is mentioned in our welding Specification that after for Example 2 time repair of Piping, New Defect shall be removed by Cut out; this removal shall include HAZ removal. HAZ per some handbook is 2 mm and macroethced of WPQR samples shows discolored part of base metal is between 1 to 4mm based on thickness of material. When Cut out shall be done if you remove HAZ(2-3mm of each side of weld metal) from base metal then your gap will be about 10 mm which is not so practical because of fixed length of Spools, so for my question consider a joint between a pipe and elbow in a fixed line;
What do you do in reality in your company?
a. Do you Cut and expel elbow with additional length of pipe from both side of elbow and replace it with new elbow and pipe pieces; what about cost of these new material?
b. If you cut only the weld; isn’t this type of cut out more harmful than conventional repair?

thanks for sharing your knowledge and experience

 

[DekDee]

pedro84,
You cut out the weld and install a "pup piece".
The length of this pup piece will be governed by your specification (proximity of circ welds)- not by any code.
If it is not noted in the specifications the length should be approved by the relevant piping engineers.
It is called CYA,
Cheers,
DD

 

[petro84]

Dear DekDee

thanks for your post; Can you please write what CYA stands for? or make a reference to what you declared above.

Thanks

 

[DekDee]

pedro84,
CYA means "Cover your ass".
What it means is do not try to make a decision on your own based on what you are told on an internet forum.
Send your questions to the people who are responsible for designing the piping system - the piping engineers.
Cheers,
DD

 

[petro84]

Hi
I found something reliable in total specification for this type of repair:

"For 3 ½ Ni materials, as well as for austeno-ferritic duplex stainless steels, a second repair of
the same area on a given weld shall not be permitted: should a defect be repaired on a
previously repaired weld area, the whole weld shall be cut and rewelded after having restaured
the base materials to their initial condition (i.e. remove heat affected zones, damaged surfaces,
etc.). "

Bye.