HYDROSTATIC TEST ON NEW STEAM PIPING WELDS

[KOULAUNG]

For installtion of new welded-end venturi tubes to existing non-boiler external 175 psig steam piping, can anyone tell me that, under what conditions, the hydrostatic pressure tests to the new welds can be waived, and if waived, who will be reponsible for the safety operation of venturi tubes.

Thank you very much.

 

[metengr]

Koulaung;
If the installation of the venturi tubes is by welding to steam piping that is currently in service you would not need to perform a hydrostatic test of the piping system or venturi attachment welds. The hydrostatic test is typically required for new construction. I assume you are working to ASME B31.1 Power piping Code.

If this is the case, and you have no Jurisdictional requirements regarding the steam piping system, I would consider this a REPAIR. For guidance, I would use the National Board Inspection Code (NBIC) and follow the recommendations for acceptance of welded repair using nondestructive testing (NDT).

As far as responsibility for safe operation after the venturi tubes are successfully installed and have been NDT'd, this is the owners responsibility. After installation, the manufacturer and installer should be responsible for successful performance (a one time acceptance test) in accordance with your contract documents.

 

[unclesyd]

Adding to metengr's post your welding has to be done by a qualified welder and the whole procedure be
pre-approved by your AI if you use the NBIC as a guide.

If ex US it will be the jurisdictional authority for your facility.

 

[KOULAUNG]

Thank you so much for your help.

We are the 16" weld-end venturi tube manufacturer, and venturi throat had a bad weld, which caused rupture during the start up. For 170 PSIG saturated steam, ASME B31.1 only required visual examinations. The venturi tube was ordered without hydrostatic pressure test or NDE. So we did not perform any test. Should the plant owner do Hydro test or 100% radiograph examination on venturi welds before put in service? Also who is reponsible for NBIC R-2 (Form for alternation) report?

 

[metengr]

I would perform a 100% RT and/or surface examination of the attachment welds in accordance with B31.1, Table 136.4, not a hydrotest.

As far as the NBIC Form R-2, the design firm signs Form R-2 for responsibility of the alteration design, the firm that installs the venturi throat signs the Form R-2 as the construction organization.