Pipe Bend Radius

Based on my actual experience as the Engineering Manager in a Pipe Fabrication Shop I say the following:

1. Before we sign the Contract you must tell me if you will have "Bends" (elbows are not bends)

2. If you say yes, you will have "Bends" then I will tell you that you must state in the "Contract" what the bend radius is to be based on. Is it some factor of the "Nominal" diameter or the literal diameter.

3. Or you must show a specific radius dimension for each bend

hello,

As per ASME B31.1-2004,Table 102.4.5,page no.14 ,states pipe diameter in pipe bend radius (e.g 5 pipe diameter or 6 pipe diameter) is nomial diameter .This shows it is based on DN(Nominal Diameter,mm), not NPS(Nominal Pipe Diameter,inch) or Outside diameter of pipe.So,I think there is no question of showing this in contract as to be based of NPS or OD of pipe.

The nominal pipe size is equal to outside diameter for pipe size 14 and +

Regards,

Hamad

You may be have some confusion related with the Nominal Pipe Size NPS, and Outside Diameter OD. Where as a standard and as indicated in post #2 by cr4hmb, the pipe with diameter 14" and more has a NPS = OD (e.g. pipe with NPS 20 has an outside diameter equal to 20" exactly).

And for pipes with diameters 12" and less, the NPS ≠ OD and NPS ≠ ID. And it is used to deal with standard pipes with its NPS and Sch., where dealing with nonstandard pipes (tubes) is through its OD and wall thickness.

And when we denotes to pipe with its D, we mean its NPS unless there is other clear indication. So, the radius of Short Radius SR elbow = 1 D and radius of Long Radius LR elbow = 1.5 D.

For bend which is differers than elbow as indicated in post #1 by PennPiper, the Bend Radius is related to its D, which means its NPS unless indicated. For example, for a bend with a radius 5D, it means 5 NPS, unless indicated.

As per ASME 31.1 Code,"D" noted is Nominal diameter(DN) of pipe not Nominal pipe size(NPS).

e.g for 5D, pipe bend radius=5*D(Here "D" is Nominal diameter)

See note C:Pipe diameter used for pipe bend radius calcualtion is Nominal Diameter (DN) of pipe.

Dear sir,

As , I understand for seemless elbow 90 deg. /45deg. is covered in ASME B 16.9 or MSS SP43. But I also want to know which is the standard for 'pipe bends'or it is manufactured as per cutomer's requierments /drawing.

Thank you.

V.D.DEODHAR.

V.D.DEODHAR.

'Pipe Bends' are manufactured per customer's requirements/drawing.

hello,

ASME B 16.49-gives information regarding pipr bends.