Bolting for body flamnges and manway 1

[jtseng123]

Dear all,
We have new vessel with standard bolt length for body flanges and manway. Client requests to use longer bolting for bolt tensioner at jobsite. It is too late to replace with longer bolt for the shop hydrotest.
Can it be hydrotested with the standard bolt length, then after shipped to job site, simply replace with longer bolt and put into service without additional hydrotest ? similar to spare bolting which is not hydrotested.

 

[SnTMan]

jtseng123, you should be able to do this. Replace a few at a time, don't break the joint. Someone in authority at site (AI or whoever) should concur.

Regards,

Mike

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

 

[r6155]

Please, can you tell us diameter and quantity of bolts for the body flange?

Regards

 

[Trestala]

If gasket compression wouldn't go below gasket seating when removing a bolt at a time, you should be able replace them as SntMan said?

 

[BJI]

After it has been seated you can go below the seating stress, same would apply when using collar bolts to retain a TS gasket, just make sure there is sufficient load to retain the gasket in place without moving. Regardless, there is no need to re-hydrotest after fabrication is complete.

 

[jtseng123]

Dear all,
Once vessels shipped to site, we will replace all shipping gaskets with service gaskets for body flanges (open the body flanges to install special internals) and manway, so there is no concern of gasket seating stress or partial replacement. We will replace all. The diameter for bolt tensioning is greater than 1". This is too extreme but we have to do as requested by client. There are many vessels so the quantity is hundreds.
The question is: can I replace with bolting which are not hydrotested with the vessels ?

 

[r6155]

jtseng123
Two different systems are torque and hydraulic tensioning.
The fabricator of PV must indicate the amount of elongation (stretch) of the studs for hydraulic tensioning, and this system shall be used for ever in this PV. Qualified personnel is required.

For studs 1” and over torque wrench is not recommended (not allowed in my practices). Torque can be damage the flanges. See ASME PCC-1 Guidelines for Pressure Boundary Bolted Flange Joint Assembly, Training and Qualification of Bolted Joint Assembly Personnel.
4 studs are tensioned at the same time.
By this reason I suggest Hydrostatic pressure test with the long studs and hydraulic tensioning.
Analyze the scope of the manufacturer's responsibility, be careful.

Hope it help

Regards

 

[SnTMan]

jtseng123, oh, you are breaking the joints anyway. I doubt any benefit to hydro'ing new bolts or new gaskets for that matter. However the bolted joints must be proven leak-free before the vessels are placed in service. Several means exist, including perhaps full hydro.

A post construction code may be applicable, definitely agreement among the parties is needed.

Regards,

Mike

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

 

[marty007]

You never did state what code of construction this vessel is built to... I am going to assume ASME VIII-1.

ASME VIII-1 is a construction code for new equipment. Once the vessel has had the ASME mark applied and U-1 form signed, this code is no longer applicable.

So, the replacement of flange bolting would be subject to the NBIC (National Board Inspection Code). Paragraph 3.3.4.2(e) classifies replacement of defective bolting as a repair:

3.3.4.2(e) Defective Bolting: Defective bolting material shall not be repaired but shall be replaced with suitable material that meets the specifications of the original code of construction.​

Later in the code, paragraph 4.4.1 lists test or examination methods applicable to repairs. One or a combination of the following methods shall be applied:
[ul]
[li]Liquid Pressure Test[/li]
[li]Pneumatic Test[/li]
[li]Initial Service Leak Test - only allowed if allowed by the original code of construction[/li]
[li]Vacuum Test[/li]
[li]Nondestructive Examination (NDE)[/li]
[/ul]

Based on these options, I think the Liquid Pressure Test would be your best bet. Note, the NBIC liquid pressure test does not necessarily have to equal the hydrotest pressure per ASME VIII-1. Paragraph 4.4.1(a)(1) states:

Pressure tests shall be conducted using water or other liquid medium. The test pressure shall be the minimum required to verify the leak tightness integrity of the repair. The test pressure shall not exceed the maximum liquid test pressure of the original code of construction. when original test pressure included consideration of corrosion allowance, the test pressure may be further adjusted based on the remaining corrosion allowance.​

Just my point of view, do your own reading of the NBIC code...

Cheers,
Marty

 

[r6155]

Suppose the hydraulic test was done in the manufacturer's workshop and the next day the new bolts arrived. Can someone say that the new ones are installed and nothing else needs to be done?.

Regards

 

[marty007]

The AI for our shop reviews all material test reports (MTR), including studs and nuts. Once the U-1 form is signed (normally same day as hydrotest), the job is done in the eyes of the AI.

If we want the new studs to be represented by the U-1 form, we would need to rip up the originally signed U-1 form. The AI would need to review the MTRs for the new studs, and would require a new hydrotest. Only then would he sign a new U-1 form that represents the new studs.

The alternative is to proceed as per NBIC as I discussed above.

 

[r6155]

Please wait a moment.
Before doing the hydrostatic test it is necessary to do the written JOINT ASSEMBLY PROCEDURE, as it is done for a welding procedure.
It is the responsibility of the pressure vessel manufacturer to indicate how much the bolt stretch is.
Who will carry out the hydraulic tensioning in this case? The manufacturer or the user?.

I take the moment to comment on the difference between torque and stretching. Torque does not consider bolt length, but stretching does. Big difference.

Regards

 

[jtseng123]

Finally, we have our AI, and his fried also AI, and AI of the shop, all confirm that no need to do additional hydrotest at site by replacing bolting, as long as bolting meets ASME code and material grade.

 

[r6155]

I am not convinced and I am not satisfied with AI's answer. It is not an answer that should be accepted by a responsible engineer. We already know that the bolts are according to ASME, but this does not guarantee the success of the hydrostatic test.

Regards

 

[SnTMan]

jtseng123, good result for you, thx for the follow-up

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

 

[saplanti]

It may not be related to the discussion, however I have to say that the hydraulic tensioners need longer bolt length to be able to use the tensioner. Your client may be asking for the tools available at site or asking for more reliable tool to tight the bolts for operation. Perhaps, the same could be used for the test. Additionally they probably want to control the strain in this way.

I guess you need to be in good relationship with your client, and you’d better discuss the issue with them.