# Co-Efficient of Friction for pipe supporting during Stress Analysis using Caesar II

All piping stress engineers must be aware that while modeling supports or restraints in Caesar II input spreadsheet we have to enter the frictional co-efficient. The value of this co-efficient depends on the supporting surface material and surface roughness. During project bidding stage (ITB Document) the client generally provides the information regarding which friction factor to be used for which surface. Also every EPC organisation prepares their own guideline for using standard friction factor in case not available in ITB document. The following write up will try to provide an idea regarding which co-efficient of friction to be used in what situation. This can be used as a guide only. However project specific data or information will override any word mentioned here.
• Coefficient of friction factor depending upon the supporting interface (i.e, junction between Top of Steel and Bottom of Pipe or Bottom of Shoe/Cradle) shall be applied at all vertical restraint (+Y or Y supports) locations as mentioned below. But if ITB for any project provides separate data then those data shall be considered.
• Carbon Steel to Carbon Steel: 0.3
• Polished Stainless Steel to Polished Stainless Steel/Graphite: 0.15
• Teflon to Teflon/ Polished Stainless Steel: 0.10
• Concrete to Carbon Steel: 0.4
• Pipe to Roll Support: 0.01
• Teflon to Carbon Steel: 0.2
• There is various philosophy among EPC companies regarding the use of co-efficient of friction for guide and directional anchor supports. Some organisation prefer not to use any frictional co-efficient for horizontal supports. However if used the same can be taken from the above table (normally 0.3 is used if no special arrangement is made).
• No friction factor to be used while supporting using rigid hangers.
• In case when Sliding Plate is required, put the comment as “(PTFE/Graphite) Sliding Plate Required” and mention friction factor μ=0.1 /0.15 respectively depending on temperature” on stress sketch. Use Teflon (PTFE) Slide plate up to a Temp of 204 degree Centigrade, above which use graphite plate (up to 540 degree Centigrade).
• Normally the friction factor shall not be applied when modeling bottom type spring. But sometimes ITB document/Client could insist for friction modeling of bottom type springs, in that situation friction factor could be applied as per requirement.
• When the pipe/shoe is supported on the welded rod on the structure then friction factor of 0.25 shall be considered.

Anup Kumar Dey

I am a Mechanical Engineer turned into a Piping Engineer. Currently, I work in a reputed MNC as a Senior Piping Stress Engineer. I am very much passionate about blogging and always tried to do unique things. This website is my first venture into the world of blogging with the aim of connecting with other piping engineers around the world.

## 15 thoughts on “Co-Efficient of Friction for pipe supporting during Stress Analysis using Caesar II”

1. john says:

Thanks

2. sathya says:

Is is necessary to apply friction at anchor points and limit stops ?

1. Bisai says:

Anchor means fully locked in the 6 direction by welding with structure. There is no possibility of sliding.How friction will come?

3. Paldex says:

With reference to Sathya, Is it also to include friction at Guide locations ?

1. want2learn says:

As per Standard industry practice friction is not considered for guide and line stop supports. However practically there will be friction. So its up to you whether to use friction or not. Check client requirement regarding the same.

1. Bisai says:

It is depend on the arrangement/type for guide and line stop support. If you use strut/restrut/ 3way (rest+guide+ axial stop) shoe support without gap then friction is not applicable.

4. Ray says:

Where should I add friction factor in CAESAR II piping input for bottom type spring ?

Thanks.

1. Bisai says:

It is available in the Caesar II manual.

5. Bisai says:

Is it applicable for all size pipe?

6. Miguel Ortega says:

Hi from mexico,

How should I consider friction if i have a antivibrating support that uses rubber.

Related to this, I have some doubts about the gap too, because rubber is elastic so, when pipe expands there is a movement allowed by the rubber, I´m very interested to know the opinion from a more experienced person, I have looking all around but I have not found anything about this, so I think it is more related to experience considerations.

(sorry for my english)

7. DSB123 says:

The friction factors quoted are significantly different to those from engineering text books especially the steel to steel value of 0.3. How can such a low value be substantiated in view of this?

8. Gi hyeok Jang says:

Thanks a lot for your always kind and informative post.

I’m a piping stress engineer in DSME and want you to advise on how to apply co-efficient differently for the following cases in Caesar II.

1. When using U-bolt(Carbon steel) with Teflon sliding pad to support carbon steel pipe.
2. When using Plastic clamp(Polypropylene) to support carbon steel pipe.

As far as I know, Plastic clamp is preferred to be used to support the lines with high pressure and I currently need to know the differences between two restraint types above in Caesar II programme.

9. dsb123 says:

I see nobody has any comment regarding to exceptionally low friction factor of 0.3 for steel to steel. The use of this value is against all recognisable engineering data – so why do people not question it???

10. M Raguramrajkumar says:

Simply follow the client requirements and provide. It will be vary from client to clients

11. Sanjiv Gandhi says:

Thanks for the awesome post.