In-line Valve Repair and Maintenance

Save time and reduce your operational costs by partnering with SVI Industrial for full turnkey repair and maintenance service for your in-line valves.
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SVI Industrial’s unique ability to combine machining, welding, millwright and valve repair services under one umbrella, allows us to offer top quality repair services for your welded in-line valves in accordance with ASME section I and B31.1.

Our extensively trained personnel use proprietary and specialty developed welding and machining equipment to repair a variety of in-line valves from all the major manufacturers. We routinely perform repairs of code boundary valves. These repairs are performed in accordance with the guidelines of ASME Section I and National Board Inspection Code as well as Jurisdictional requirements. We also perform in-line valve servicing as part of the boiler external piping. These in-line valve repairs are typically performed following the guidelines of ASME B31.1.

SVI Industrial is uniquely equipped to perform the following repairs on welded in-line valves:

1. Valves requiring a seat (s) (Rings) replaced:

Often times, these repairs can be “R” stamp repairs. We typically see the entire seat ring to valve body welds having cracks in the partial penetration welds. Our customers also experience hardface material missing from the seat face. In order to replace the seat rings within an in-line valve, the following steps are followed:

  • All seat pockets are measured to ensure new seat fit.
  • If dissimilar welding is performed on original seat, all old metal is removed and then acid etched to ensure complete removal. Reweld with base metal and machined to size. NDE (Dry MT)(magnetic particle testing) of the new pocket.
  • Minimum preheat 400o F
  • Welding process machine GTAW (gas tungsten arc welding)
  • 035” ф dia Wire – Er90S-B9 GTAW
  • Mn + Ni chemistry <1.0
  • PWHT (post weld heat treatment) @ 1375o F – 2 hours soak time minimum
  • Thermocouples and ceramic pads on ID seat area
  • Final NDE (PT) (dye penetrant testing) and (VT) (visual testing)

2. Removal and re-welding of Integral valve seats

We also help customers who have experienced cracks in the in-line valve seat area hardface going back into the base material of integral valve seats. Some of the guide ribs also show severe cracking. We have extensive experience repairing cracking in the guide ribs. In a typical integral valve seat replacement, the weld repair usually requires the removal of the stellite and undercutting the base material. Both rewelding of base metal and then applying hardfacing is required.
Integral seat repairs use the following guidelines:

  • Remove all the hardfacing and .080” – .100” of base metal.
  • Insure all visible defects are removed
  • NDE (PT) inspection of all repair areas
  • Sketch and dimension all repair areas
  • Preheat the valve to 400o F minimum. Note: 300o F for (P-4) material
  • Weld excavated repair areas and undercut area with Er90S-B9 (Er80S-B2 for P-4 material)
  • Profile all the repair areas and NDE dry (MT) on all P15E materials.
  • Keep base material at 100o F. No moisture is allowed on “as welded” 15E materials. NOTE: PT or wet (MT) is allowed on all other low alloy materials.
  • Re-establish 400o F [reheat]
  • Apply minimum of (2) layers of stellite 21
  • Cool valve to below 175o F and visually inspect welds
  • PWHT minimum hold 2 hours @ 1375o F per heat treat traveler. NOTE: PWHT temp 1250o F for P-4 material
  • Profile the seat and guide ribs to OEM specifications
  • Final NDE, PT to ASME Section I and VT to ASME B31.1
  • An authorized inspector will review the weld data package and issuance of R-1 form and data plate as required

3. Repair of cracks in the valve body or on the guide ribs or disc guides.

SVI has a quality control system, meeting the requirements of Mandatory Appendix J of the ASME Section B31.1 Code for the weld repair of section I welded in-line valves.
B31.1 requires the following as a minimum be documented:

  1. Removal of defect or reduce to acceptable size
  2. NDE of defect area either by PT or MT, acceptance criteria per Chapter V- 136.4.3 for MT and 136.4.4 for PT
  3. Preheat of the base material as required in Chapter V-131 “Welding Preheat”
  4. Welding shall be performed by use of PQRs (procedure qualification records), WPSs (welding procedure specifications) and WPQs (welder performance qualifications) as outlined in Chapter V-127.5
  5. PWHT of repair as required by Chapter V-132 “PWHT Requirements”
  6. Final NDE of the repair as required in Chapter V-136.4 “Examination methods for welds and repairs”

SVI Industrial has the specialized machining and welding equipment and expertise to repair each type of in-line valve. Our technicians, welders and machinists receive specialized training on the equipment, as well as the SVI’s standard operating procedures.

For more valuable information on our in-line valve repair and maintenance capabilities, be sure to see our article published in Valve Magazine discussing how to determine whether to repair or replace check valves.


Our turnkey In-line valve repair and maintenance services will save you time and reduce your cost of operations:

      • 24/7 Emergency Service
      • Valve seat removal and reinstallation
      • Seat lapping
      • Welding and heat treatment
      • Specialty Machining
      • Custom machined and fabricated parts meeting OEM standards
      • Factory trained actuator repair
      • State of the art mobile equipment and tools
      • Seven fully stocked mobile repair shops
      • One company and point of contact from the start of your project to the finish