field cold bending - Pipelines, Piping and Fluid Mechanics engineering (2024)

×

INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!

  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

Join Us!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Eng-Tips Posting Policies

Contact US

thread378-258983

ForumSearchFAQsLinksMVPs

field cold bending

field cold bending

pipeliner3000 (Petroleum)

(OP)

General rule of thumb for field cold bending (onshore pipelines) is 40D bend raius. Does anyone know the origin of this?
Further, for large diameter pipes this gives fairly sensible bends achievable for a double random pipe length (12m).
Calculated for 8" pipe using arclength = r * theta and assuming 10m bend arc you get 8.5degrees / m - 85 degress for one pipe joint...

I can't see 85degrees happening on a field bending machine. Is the machine the only limitation?

Is there a general rule of thumb that 10degrees per joint is maximum sensible bend... or am i missing something..!

Replies continue below

Recommended for you

RE: field cold bending

SNORGY (Mechanical)

The rule of thumb they refer to in CSA Z662-07 for 12"-D pipe is 1.5 degrees change in direction per pipe diameter of arc length.

I prefer to evaluate things in terms of outer fibre elongation; the ASME B31.3 Code for impact-tested material would limt outer fibre elongation to 5%.Since most line pipe in industry (here anyway) has some impact test qualification to Category III or Category II, you could probably "get away with" 5% elongation, but without field hardness testing I wouldn't want to go there.

I read somewhere in a myriad of articles about a year ago that common practice in the USA P/L industry is to limit outer fibre elongation to 2% - 3%, thereby permitting cold field bends in the (approximately) 25-D radius range.

Regards,

SNORGY.

RE: field cold bending

rneill (Mechanical)

You might want to look at the document ES-24 published by the Pipe Fabrication Institute as it provide some guidance on acceptable cold bend radius based on the method in use (type of machine).

General rules of thumb that I've used for cold bends are as follows:

10" and smaller with a polyethylene coating, no less than 30D (2 degress per diameter of length) to prevent damage to coating.

12" and larger with polyethylene coatings, no less than 40D (1.5 degrees per diameter of length).

All all pipe with fusion bonded epoxy coatings, no less than 40D (1.5 degrees per diameter of length).

For uncoated pipe, I default to the Design Code in use (B31.3, B31.4/8, or Z662).Note: Look at Clause 841.23 of B31.8 as I think it has quite a bit of guidance.

Note also that anything with fiber elongation more than 5% (a 10D bend) in sour service requires stress relieving or heat treatment per NACE MR0175/ISO 15156.

RE: field cold bending

BigInch (Petroleum)

In the pipeline codes B31.4 & B31.8
you will find the minimum permitted bend radaii in,

B31.4PP 406.2
B31.8PP 841.231

B31.4 is quoted as follows, and
BOTH CODES HAVE THE SAME IDENTICAL TABLE

[quote]
(b) Except as permitted under para. 406.2.l(c), the
minimum radius of field cold bends shall be as follows:
Minimum Radius of
Nominal Pipe Size Bend in pipe Diameters
NPS 12 and smaller 18D
1421
1624
1827
NPS 20 and larger30

**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/

RE: field cold bending

GregLamberson (Petroleum)

pipeliner3000

Depending on the pipe, you can generally get a little more than 10 degrees though.For example, currently working with some 24", X-65, 1.000" WT API 5L pipe and we are getting up to 12 degrees per joint with the cold bend trials.

Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website: www.oil-gas-consulting.com

RE: field cold bending

pipeliner3000 (Petroleum)

(OP)

Thanks, all suggests that 40D bend is not the minimum for 6" pipe. However, 40D gives 8.5 degrees per metre (85 degrees in 1 joint)that I don't believe can practically be pulled in on a standard field cold bending machine.

Any ideas what might be acheivable??

RE: field cold bending

BigInch (Petroleum)

Buy a 5D90 and field cut it.

**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/

RE: field cold bending

rneill (Mechanical)

You could call your contractor and ask him what he can do with his machine?

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login



News


Close Box

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

  • field cold bending - Pipelines, Piping and Fluid Mechanics engineering (2)Talk To Other Members
  • Notification Of Responses To Questions
  • Favorite Forums One Click Access
  • Keyword Search Of All Posts, And More...

Register now while it's still free!

Already a member? Close this window and log in.

Join UsClose

field cold bending - Pipelines, Piping and Fluid Mechanics engineering (2024)

FAQs

What is a cold bend in a pipeline? ›

Cold bends are frequently required in energy pipelines in order to change the vertical and horizontal orientations of the pipeline route. They are produced by plastically bending a pipe joint in a cold bending machine by creating a series of uniformly spaced incremental bends.

What is the difference between hot bending and cold bending? ›

Cold bending methods often rely on sheer physical force to help bring the pipe to its final shape while hot bending methods use careful heating to reduce the force required. Each method has unique benefits and will determine the degree of bending possible and the final shape of the pipe.

What is a field bend? ›

As defined in section 404.2. 2 of ASME B31. 4, Field bends are cold bends made in the field during pipeline construction to allow the pipe to conform to the contour of the ditch.

What are the advantages of cold bending? ›

Cold bending is most effective with sheet metal, which is more pliable than thicker metal stocks. It is especially useful for bending tubes and pipes. It also helps to produce smoother and more gradual curves and bends in the metal. Cold rolling also can strengthen metal, whereas heat tends to weaken it.

What is the minimum inside radius for cold bending? ›

Cold-bending guidelines for shapes are also found in the AISC Manual, Part 2 Section: 1. "The minimum radius for camber induced by cold-bending in members up to a nominal depth of 30 in. is between 10 and 14 times the depth of the member. Deeper members may require a larger minimum radius."

What is the difference between elastic bend and cold bend? ›

Elastic bends – where the pipe is allowed to bend elastically and elastic stresses remain in the pipeline. Cold bends where the pipe is bent plastically in the field using a bending machine - usually to a radius of 40D and angle <15 degrees.

What are the disadvantages of cold bending? ›

The main limitations of cold bending involve the thickness of the metal and the complexity of the desired shape. Very thick or high-strength metals may require hot bending to achieve sharp or tight bends without cracking.

Does cold bending weaken steel? ›

During testing it was determined that cold-roller bending of steel leads to significantly reduced yield strength where the material is in compression during bending.

What is the difference between hot rolled and cold rolled bending? ›

Cold-rolled steel is also more ductile than hot-rolled steel. In other words, it can bend under greater stress without breaking. With cold-rolled steel being more ductile than hot-rolled steel, manufacturers can work with it more easily, manipulating the metal's shape to fit their needs.

Why do pipelines have bends? ›

Some line pipes will require bending to accommodate changes in direction in the pipeline alignment and elevation of the trench. Bending can be done before or after trenching is completed.

What are the different types of pipe bending? ›

You'll encounter the following: compression bending, rotary draw bending, roll bending, and mandrel tube bending. Each of these processes achieves a precision bending in order to make the pipe suitable for application, depending on the purpose.

When cold bending a pipe, the bending radius should be approximately? ›

Generally speaking, the minimum bending radius should not be less than 2-2.5 times the outer diameter of the pipe, and the shortest straight distance should not be less than 1.5-2 times the outer diameter of the pipe, except in special cases.

Why should you use a bent pipe instead of a fitting? ›

Not only do tubing systems offer easier installation, but tube bends can save operators time by eliminating the need to cut, deburr, and install a new fitting for every simple directional change. Less turbulence. Bends allow fluids to flow more easily than through a series of multiple fittings.

Is it better to heat metal before bending? ›

Any dirt or debris on the surface will make it more difficult to bend. Next, you need to heat the steel. This step is only necessary if you are using the hot forming method. If you are using the cold forming method, you can skip this step.

What are the disadvantages of cold working metals? ›

Some disadvantages and problems of cold working are:
  • The metal is harder, calling for greater forces, harder tools and dies, and heavier equipment.
  • The metal is less ductile and malleable, limiting the amount of deformation that can be obtained.
  • Metal surfaces must be clean and scale-free.

What is cold bent? ›

Cold bending is one of the most commonly used means of forming steel into many different configurations. The process is performed using rollers to press a piece of steel against tools called dies or mandrels.

What is a cold forming bend? ›

Creates a tighter fixed bend than the minimum unsupported plastic pipe allows. JG Speedfit cold forming bend helps create a tighter bend than the minimum allowed when the pipe is unsupported. Designed, manufactured and assembled in the UK.

What is a cold cut on a pipeline? ›

Cold Cutting refers to cutting pipe without the use of heat from a torch (hot cutting) where open flame is used.

Top Articles
Latest Posts
Recommended Articles
Article information

Author: Carlyn Walter

Last Updated:

Views: 6019

Rating: 5 / 5 (70 voted)

Reviews: 93% of readers found this page helpful

Author information

Name: Carlyn Walter

Birthday: 1996-01-03

Address: Suite 452 40815 Denyse Extensions, Sengermouth, OR 42374

Phone: +8501809515404

Job: Manufacturing Technician

Hobby: Table tennis, Archery, Vacation, Metal detecting, Yo-yoing, Crocheting, Creative writing

Introduction: My name is Carlyn Walter, I am a lively, glamorous, healthy, clean, powerful, calm, combative person who loves writing and wants to share my knowledge and understanding with you.