Effect of reducing wall thickness and increasing SMYS

[edwyn]

Can an increase in the SMYS of a pipe account for a reduction in wall thickness
E,g Substituting API 5L X65 WT 38.1mm for API 5L X60 WT 39mm

 

[LittleInch]

Yes, the increase in SMYS would more than acocunt for the change in wt for a pipeline design code. For B31.3, you need to look at the tables as the Xgrades sometimes don't increase the allowable stress as much as the SMYS increase.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[weldstan]

edwyn,
It appears that B31.3 is your design Code since you have only lowered T by .9 mm and the design allowable is only increased by < 3%. You'd get over 9% increase in the design allowable for X70. Wheras the majority of X65 meets X70 requirements, substituting X70 for X60 would seem a mrre economical approach.

 

[edwyn]

Liitleinch and Weldstan many thanks for your info If i have API 5L X65 wt 38.1mm already procured can i use this material as a substitute as already mentioned above

 

[LittleInch]

I think you can propose it to whoever asked you to provide the original pipe, but I cannot be responsible for what you do as I have no knowledge of your system, design code or any technical responsibility for your project. You need to discuss this with the person or organisation who does.

I've just answered your question as best I can.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[weldstan]

Do the calculations according to the applicable Code to support its use. After that, see LittleInch and if you are not the Owner, ask him. If you are not the responsible Engineer, ask him.