Does Anybody Have Bolting problems ? 1

[dcharles]

Does anybody have any bolting problems in the working environment ? If so let me know, I am intersested in this area of study.


D

 

[jici]

The problem we have is as follow:

on PTFE lined steel pipes, after one thermal cycle, the bolt torque decreases because of plastic liner deformation and bolts relaxation. It does not mean that it's leaking but we are wondering what is the usual practice with regard to retorquing.

We let the pipes cool down and releive the pressure but when the workers do the retorquin, the pipes are still full. They want to know if they have to emty them.
Thanks,

 

Are you aware of this web site?

http://www.boltscience.com/index.htm

 

[sprintcar]

dcharles - we occasionally have to evalute the bolt stress in both flange fasteners as well as the bolts holding the pump to the foundation -
Problems are poor installation technique, torque (undefined, wrong, incorrect tools, wrong pattern) thread lube, metric vs sae, etc.
Life in the field is a lot different than the CAD layout shows......

Direct email
bcourtwright@giwindustries.com

 

[GaryGrubert]

This is a very big area of concern for most reliability engineers and maintenance managers in the chemical, pulp and paper, refinery and power generation industry.

MTI (Materials Technology Institute

http://www.mti-link.org)

is currently developing a Flange Make-up project that will be used to instruct and potentially certify pipe-fitters.

Improper installation and the lack of subsequent retorque procedures after initial thermal and pressure cycling of piping systems cause bolt relaxation and this is directly related to the majority of bolted joint failures in the field.

My company is involved in the PVRC/ASTM efforts to develop new gasket contants that will replace m&Y values. Most major manufacturers of gasketing materials have developed
bolt torque recommendations based on the physical properties of their materials. As a reference check out

http://www.durlon.com.

Hope this helps.

Best Regards,
Gary Grubert
Durabla Manufacturing Company
ggrubert@cinci.rr.com

 

[Teeboog]

Belleville washers are a good fix for flanged connections that thermal cycle. The washers are concave and provide spring tension on the stud to maintain the gasket seating force.

 

[edemarcos]

I need to use metric bolt on Ansi 150# 24'' flanged joint.
B16.5 requires 1-1/4'' bolt ( O.D. = 31.75 mm )
There is a code o standard rule to select M30 or M33 ?
Or I must perform a calculation according to ASME code ?
( A bolt with OD=32 mm does not exist )

Many thanks in advance