Introduction to Vendor Drawing Review
Vendor drawing review (VDR) is a review of valve drawings indicating cross sectional view, material of construction with respect to purchase requisition (PR)requirements / data sheets.
Piping material engineer shall well understand the Project/Client/contract specifications to take care of any requirements specified therein which need to be reflected in the drawing before taking up this work on the project. Piping material engineer has to be familiar with codes applicable for the respective valve type.
You may refer to specific requirements based on various valve types here
General Requirements for Vendor Drawing Review
Below mentioned are general requirements which are applicable to most of the manual valves.
Following details with respect to relevant valve data sheets, PO/PR shall be checked:
- Tag no/Part Number/Client part number, Size, MR SOS item No, Type of valve.
- Project specific Datasheet document number.
- Pressure class designation as applicable.
- Valve Design Standard specified (such as API, BS etc.).
- End connections (threaded, socket welded, butt welded, flanged, wafer type or hub ended). In the case of jacketed valves, the jacket flange size may be valve or jacket size depending upon whether the valve is partly or fully jacketed. Check for jacket fluid inlet / outlet connections. In case of valves with special end design, flanges / hub dimensions shall match with flanges / hub procured.
- Pipe class as applicable.
- Bonnet design whether welded or bolted or pressure seal type.
- Valve pattern i.e., long or short pattern requirement.
- Type of flange facing Raised face/ Flat face/RTJ with surface finish. In case of RTJ flange, hardness value.
- Materials of construction for:
- Pressure parts (Body, Bonnet/Cover, Ball/Gate/Disc).
- Pressure bolting with coating if any.
- Trim (Seating surface/Seat Ring, Stem), Trim no.
- Design temperature.
- Gland packing or seal material.
- Spring Material.
- Bonnet/body gasket material.
- Jacket of jacketed valves.
- Other accessories shall be checked for suitability to service conditions like Low Temperature (LT) material for applications where in the ambient temperature is – 45 deg. C
- Type of operation where applicable, such as lever/wrench with position indicator, hand wheel, Gear, Chain etc., Or if extension of stems are required-in case of valves with insulation / extended operation. Check the extended stem dimension according to layout requirements.
- Stem design shall be generally single piece construction, however for extended stem design two piece construction shall be reviewed and may be accepted based on integrity and functionality of design provided by suppliers.
- Body wall thickness provided by vendor (actual) and body wall thickness as per respective design standard.
- Additional thickness considered in the shell for pipe classes wherever it is specified with Corrosion allowance ≥ 6 mm.
- Locked-open /Close requirements.
- For valves with butt-welding ends, edge preparation details and connecting pipe wall thickness details.
- Jacket fluid details.
- Tag/Name plate as per project specific requirements.
- Painting requirements as per project specifications.
- Compliance to NACE MR-0175/NACE MR-0103/ISO-15156 as applicable for sour service.
- Reference to compliance to Job specification, NDE specification requirements.
- Flow direction for uni-directional valves.
- Spark test requirements for liners, as specified.
- Weight of valves especially for large sizes including gear box.
- Test pressures for Hydrostatic Shell, Seat /back seat, Pneumatic Seat.
- Fugitive Emission type test & production test, LT tests, Fugitive Emission tightness class requirements if any.
- Overall dimensional details i.e., face to face dimension etc., flange details or flanged end valves, in case of ball valves outer body contour dimensions from centerline to avoid interference with adjacent piping for sizes where it is more than outer diameter of connecting flange etc. distance from centerline to gear box location, hand wheel orientation for PDMS / PDS modeling.
- Supporting details for large size valves and lifting lug details. Minimum 2 Nos lifting lugs are required for valves weighing 250 Kg and more.
- Maximum wheel diameter (normally minimum of 750mm or face to face) or lever length (normally minimum of 450mm or twice the face to face) as per project requirement.
- End flange standard especially for sizes above 24” whether it is as per B16.47 Series A or B/ API standard.
- Wafer type valves, where the disc is expected to come out of body in open condition, clearance of disc with connecting pipe ID to be verified.
- Deviations in material of construction if to be accepted because of superior metallurgy offered by vendor to be scrutinized cautiously e.g., SS body proposed in place of CS shall lead to de-rating of CS rating.
- All nonmetallic seals shall be ascertained as suitable for service intended for. In particular, this shall include where applicable for the pressure rating, temperature,Sour service, fire-resistant and explosive decompression.
- Check if the extended bonnet requirement is applicable.
- Check if ‘O’ rings are provided in the vent/drain connection.
- Check for Full vacuum requirement compliance specified in the drawing.
- Check for PSL level and PR requirements for valves designed according to API-6A standard.
- Check for ring number requirement for flanged end valves designed according to API-6A.