Differences between Table 1, 2, 3 and 4 in ASME Section II Part D 1

[PipelineEgr]

Hi, Does anyone knows the differences between table 1, 2, 3 and 4 and ASME Section II Part D? They seems to have different allowable tensile stress ratio (e.g. 1/4xSMTS, 1/3xSMTS, 1/3.5xSMTS). What table is applicable for a bolted flange design? My guess would be either 3 and 4 since the table description mentions bolting under the Product/Material header as seen below:

Can any1 clarify? Thanks

 

[SnTMan]

See Subpart 1, pgs 2 & 3.

Regards,

Mike



The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[PipelineEgr]

Thank SnTMan,

I note that the differences lies between each classes specified in Section III. However, I was wondering if i can tweak that allowable to suit my analysis. I have an issue with the bolt tensioning required for a flange design exceeds the allowable bolt sress. The current allowable bolt tensile stress i used is 1/4xSMTS.

 

[XL83NL]

However, I was wondering if i can tweak that allowable to suit my analysis

Unfamiliar here with Sec III, but that sounds like the exact opposite of what ASME does/allows.

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

 

[SnTMan]

PipelineEgr, not clear from your posts what Code you are working to or what analysis you are performing. However the allowables in Tables 3 & 4 are to be used for design of bolted flanges. Higher stresses are (nearly) always used in assembly of bolted joints. See ASME PCC-1 for example.

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[r6155]

Be careful. Local flange distortion under the bolt also is important.
Regards

 

[iangineer]

Use ASME Sec II-D Table Y-1 for bolt yield stresses. Typically best not to exceed 70% of yield.

 

[PipelineEgr]

SnTMan, I am working out the optimal bolt tensioning required based on the pipeline and flange parameters (e.g. forces, moments, no. of bolts etc), using ASME VIII Div. 1. However, my analysis found that the required tensioning exceeds the allowable tensile stress, in which it is greater than 215MPa (1/4xSMTS). So, I am trying to figure out a way to make it work to without changing any of the flange parameters. I saw that there are other situations where the allowable tensile stress ratio is different (e.g. 1/3xSMTS and 1/3.5xSMTS). I am trying to justify if i can use that allowable since 1/3xSMTS will yield higher allowable, hence the tensioning required is passable.

 

[PipelineEgr]

iangineer, 70% seems high, that is probably equivalent to 2/3xSMTS. Will that really be okay?

 

[SnTMan]

PipelineEgr, if you are referring to Apx 2, it is not suitable for joint assembly. Get hold of PCC-1.

EDIT:

iangineer, 70% seems high

Not necessarily. The greater the bolt load, the less it is influenced by the external loading. Assuming service conditions do not cause the bolt stress to exceed yield. And that the flanges are up to it of course.

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[r6155]

@ PipelineEgr
1)What is the diameter of the bolt?, material?
2)How do you plan to control bolt stress during installation?

Regards

 

[iangineer]

60% to 70% bolt stress is normal. Some chemical companies tend to use close to 80% bolt yield for their high temperature shell and tube exchangers. Those stresses are often needed to properly seat gaskets in pipelines and keep them seated during operation. You do have to take operating temperature into account.

 

[PipelineEgr]

r6155, it is an M64, bolt will be tighten using a hydraulic bolt tensioning equipment.

 

[PipelineEgr]

iangineer, ouh wow that sounds like a good news.

 

[r6155]

I assume you use studs, not bolts.

Regards