Suitable pipeline elbow for caliper pigging operations

[jlpinem]

Dear all forum members
My company has a pipeline project of 16" pipe. we are going to change bend into elbow. we will use 90 and 45 elbow. please give me suggestion what is the minimum elbow radius which the caliper pig will be able to pass through?
Thank you

 

[LittleInch]

Why???

You are busy changing your PIPELINE into PIPING.

I don't know any instrumented pigs which are happy at less than 3D and most would prefer 5D.

Also you need to avoid multiple bends within certain distances, especially if they change orientation.

My motto: Learn something new every day

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

 

[brpillai]

Most of the Intelligent pigs should pass through 3D,however, if space is available, provide 5D. If the pig is stuck up it would be very expensive to take the pig out.

 

[Latexman]

LittleInch,

"Also you need to avoid multiple bends within certain distances, especially if they change orientation."

I'm trying to understand what you mean by orientation. Is this equivalent to "Also you need to avoid multiple bends within certain distances, especially if they change planes."

Good luck,
Latexman

Technically, the glass is always full - 1/2 air and 1/2 water.

 

[brimmer]

Typically 3D, some do 1.5D. Also depends on the ID.

 

[LittleInch]

Latxman, Yes

My motto: Learn something new every day

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

 

[Krausen]

Without much direct experience, I've heard many smart pigs can handle 3D elbows now. Some manufacturers are even claiming 1.5D/LR elbows even. Just don't go back-to-back with your elbows is the "rule of thumb" I've heard.

 

[brpillai]

when we talk about 3D or 5D it is not elbow, it is bend. There is a difference between bend and elbow. Elbow is made by forging and has a smaller radius and sharper curvature, such as 1.5 D or sometimes 3D. Bend ha s a smoother curve such as 3D or 5D or more, and are fabricated by hot induction bending for passage of pigs.

Go for 3D Hot induction bends. not elbows in your case.

 

[Krausen]

"when we talk about 3D or 5D it is not elbow, it is bend." I understand the difference, however 3D forged elbow fittings can also be used, especially inside facilities. A 3D elbow and a 3D hot bend have the same bend radius.

"Bend ha s a smoother curve such as 3D or 5D or more". Not following you there for a 3D hot bend/elbow. Both would perform the same.

3D elbow fittings may be purchased off the shelf and will likely cost you a lot less than any hot bend. They also have the advantage of a full hoop stress pressure rating, as opposed to de-rated hot bends which are typically only rated for 92% of their wall thickness due to the wall thinning that occurs during the hot bend process.

If your pig requires a minimum 5D radius or more, then obviously you'd need to go with hot bends.