API 5L question

[OwaisGillani]

hi

Is it possible in any way for the buyer to specify line pipe dimensions with constant ID and different OD? e.g. pipe of ND 18-inch but with constant ID of 425.2mm and wall thicknesses like 14.5, 16 and 18 mm. I have gone through API 5L (very thoroughly again and again)and all I find is OD and wall thickness and I have been doing it in the same way for a long time. Now some management guy is convinced that it is better to go with constant ID.

I don't have the time to go into a lengthy argument so basically I am looking for a nail-in-the-head type of reply.

Can somebody help?

 

[nickelkid]

“API SPECIFICATION 5L

7 Dimensions, Weights, Lengths, Defects,and End Finishes

7.1 SPECIFIED DIMENSIONS

boldLine pipe shall be furnished in the outside diameters boldand
wall thicknesses specified on the purchase order;”

 

[nickelkid]

Please excuse the bold formatting error in previous reply.

"API SPECIFICATION 5L

7 Dimensions, Weights, Lengths, Defects,and End Finishes

7.1 SPECIFIED DIMENSIONS

Line pipe shall be furnished in the outside diameters and wall thicknesses specified on the purchase order;"

 

[Bonswa]

If the piping that you need is 18", then you're not going to get a standard 18" pipe with the 18" on the ID. All standard piping up to 14" uses that diameter as the ID (ex: 10" pipe will have 10" ID). The wall thickness is then added to the OD. So, if that 10" pipe has .250" wall thickness, the OD will be 10.5".

Now, once you get to 14" and above, the diameter refers to the OD; and the wall thickness is added to the ID side. So, that 18" pipe is going to be 18" OD standard. if your wall thickness is .250", then you're going to have an ID of 17.5".

I hope this is what you were looking for.

 

[IFRs]

All the pipe I am familiar with has constant OD and variable ID depending on wall thickness. This applies for all sizes.

 

[Bonswa]

Refer to Table 1 in API recommended practice 574. You can clearly see the break at 14" where the pipe diameter changes from the ID to the OD. That's what I was referring to.

I'm not too familiar with API 5L, however Table 22 on page 56, Table 24 on page 63, and Table F.1 on page 95 of the specification clearly shows the exact same break at 14". Look at the left column titled "Specified Outside Diameter." In parenthesis, you see sizes up to 12.75" OD, where it's a 12" pipe, but the wall thickness is added to the OD. After that, you go to 14" OD and the wall thickness is taken from the ID. It switches around at 14".

 

[OwaisGillani]

Well guys, thanks for the replies.

I understand API 5L and I have been working with piping and pipelines for quite sometime. So I know that line pipes are specified with constant OD and variable ID depending upon thickness.

The trick questions here are;
- Whether it is possible to specify and purchase line pipes based on constant ID in real world?
- Has somebody ever ever done this before?
- Is there any pipe mill that anybody on this forum knows which produces or can produce pipes with constant ID?
- Is there any code case or clarification in this regard?
- And lastly, if done that way, can the pipe still be marked as API 5L specification?

Replies awaited.

 

[IFRs]

I'd say "no" since the flanges would not fit various ODs.