High temperature bolt material 1

[Indyvidual]

My question is:

What material should the bolts be of for a pressure vessel with the following specifications:

P[sub]design[/sub] = 68 bar
T[sub]design[/sub] = 415 °C
V = 8 dm3
Flanges: 2" and 3" 1500 RTJ.
Pressure vessel according to EN 13445.

Will 25CrMo4 be a suitable material? What bolts are suitable for these temperatures and pressures?

 

[Vikko]

the material is suitable according to EN 10269 up to 500°C.

For the flange 2"1500# and 3"1500# the bolt sizes are indicated in ASME B16.5. The Pressure-Temperature rating depends on the material of the flange (check tables 2-... in ASME B16.5), but with class 1500# at 415°C it is for sure more than 100bar with any kind of material.

 

[MJCronin]

IndyVidual...

This is a very interesting topic and there have been several excellent discussions on high temperature bolting on the eng-tips forum.

Some threads to consider:

https://www.eng-tips.com/viewthread.cfm?qid=386713

https://www.eng-tips.com/viewthread.cfm?qid=255553

https://www.eng-tips.com/viewthread.cfm?qid=179986

In my opinion, there is certainly a strong need for a quality book or comprehensive report on the selection of HT fasteners across a variety of final applications (i.e. boilers, power, aerospace and subsea) and across a variety of codes and standards. Available reference materials to the average engineer is just too fragmented or too old ...

Of course, important factors to consider in bolting selection are Code of Record, availability, temper and cost

Does anyone else have any quality reference papers to share on this topic ?

Best Regards

MJC


MJCronin
Sr. Process Engineer

 

[XL83NL]

ASME STP-PT-036
WRC 510
WRC 538 (not sure if it deals with high temp stuff)
You might consider looking for interesting articles in ASME's PVP Proceedings.

I agree with MJC that this topic isn't covered in a very coherent way in the Code books, but then again, the books arent Cook books.

Huub
- You never get what you expect, you only get what you inspect.

 

[r6155]

@ MJCronin

1) Torque vs Elongation
Torque is not good method for pressure vessels.
Torque for stud 1”x 4” is equal to stud 1” x 12”, or more longer. This is wrong.
Best practice is measuring elongation (stretching). Tensioning with wrench or by hydraulic tensioner.
Measuring with caliper or by ultrasonic device.

2) High temperature service
Avoid bolted flange. Nozzle to piping connected by welding.
Only Bolted flange for inspection opening (manhole). Use “Weld Ring Gasket” ,see “Flexitallic Design Criteria
Gaskets”

Regards

 

[davefitz]

If the flange and bolt are in steam service, please note that some high temperature bolting materials are subject to SCC , which can occur if the combination of steam and thread lubricant forms compunds of sulphur or flourine. In other words, have a metallurgist determine if the bolt has a SCC potential issue and select a thread lubricant that does not have such compounds.

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

 

[0707]

https://www.bing.com/videos/search?...A55E91D9DFBD2DADB2ACA55&view=detail&FORM=VIRE

regards

luis

 

[r6155]

Lubricant is not used when tensioning is with hydraulic tensioner.

Regards

 

[weldstan]

I have commonly seen SA 194 B7 or B16 used at 415 C.

 

[Trestala]

@r6155, that is incorrect if the purpose is to prevent seizing and minimizing corrosion.

 

[r6155]

@ Trestala
Please, see ASME PCC-1 (2019)

"Hydraulic tensioning can be very quick and accurate
when applied correctly [generally for studs M50 (2 in.)
and larger]. It also tends to improve stud life (less risk
in bolt reuse) due to lack of torsion and thread galling
(since the nut is wound down in the unloaded condition)."

Regards