Purchase order for Gaskets include Bill of Material as well as Technical Requirements for Gaskets. Sample Technical Requirements for a particular project is as shown below:
Applicable Gaskets Standards
Gaskets shall conform to the following standard, except where modified by this specification.
- ASME B16.20 for spiral wound ring type gaskets.
- ASME B16.21 for flat ring gaskets
Applicable Flange Standards
Gaskets shall be suitable for installing between :
- ASME B16.5 flanges for sizes up to 24” and
- ASME B16.47 series ‘A’ / MSS SP 44 flanges for sizes greater than 24”.
Flange gasket contact surface finish shall be in accordance with ASME B16.5.
Asbestos shall not be used for non-metallic gaskets or part of metallic gaskets. Use of asbestos in any form is strictly prohibited.
Flat Ring Gaskets
- The flat ring gaskets shall be basically manufactured out of soft non-metallic materials in the form of flat sheets and shall only be used typically in low to medium pressure general services.
- The flat ring gaskets shall be made of resilient or pliable materials such as rubber, Aramid fibre, PTFE, reinforced PTFE, graphite suitably reinforced, mica, etc.
- The flat ring gaskets shall not be used for RTJ type flanges, or male/female type flanges, or tongue and groove type flanges.
Spiral Wound Gaskets
- Spiral wound gaskets shall be provided with inner and outer rings in compliance with ASME B16.20.
- The materials of the spiral wound gasket components e.g. filler, windings, outer and inner rings, shall be as specified in the Material Requisition. The windings and the inner rings shall always be made from type 316 stainless steel or higher grade.
- Where gaskets components made from austenitic stainless steel to ASTM A240 Gr 316L are specified, the product shall be in a solution annealed condition, before assembly.
- Graphite based gaskets or where this material is used for filler material in spiral wound designs shall be suitable for temperatures up to 400 °C.
- All spiral wound gaskets in class 150 shall be of low density (low stress) type which are designed to seat at lower bolt loads.
Ring Type Gaskets
The ring type gaskets shall have a maximum Brinell hardness as specified below:
Gasket Material Maximum Hardness (HB)
Soft Iron 90
Alloy Steel 130
18/8 Stainless Steel 135
Alloy 625 180
Alloy 825 160
6% Mo 160
Source Service Requirements
All Gaskets specified for sour service shall meet the requirements of NACE MR0175/ ISO 15156 – latest edition.
Inspection and Testing
- Gaskets shall be inspected and tested in accordance with the relevant product codes and standards, Purchase Requisition and as stated in this specification.
- The Vendor is responsible for informing the Contractor about the availability of goods for inspection and testing.
- Examinations and/or tests may be reviewed and/or witnessed by the Contractor or their authorized third party inspector at the Vendor’s facility.
- Gaskets shall be tested in Vendor’s works and test certificates shall be provided as per the Supplier Data Requirement List (SDRL).
- Vendor shall submit the certificate of conformity of the material duly certified by Inspector. Type approval testing certificates for gaskets, where required shall be submitted. In this certificate the manufacturer shall confirm that the supplied product has passed type approval testing in accordance with requirements of relevant standards.
- Inspection shall be performed as per “Vendor Quality Requirement” form attached with the Inquiry / Purchase Requisition.
- Positive Material Identification (PMI) shall be conducted for all Gaskets in accordance with the PMI standards/specifications applicable to the project.
Marking and Color Coding
- The marking shall be done in accordance with the standards/specifications for marking applicable to the project and the relevant product codes and standards.In addition, the stock code number, purchase order number and purchase order item number shall be marked on each box or package.
- Colour coding shall be done based on the material categories as identified in accordance with the standards/specifications for colour coding applicable to the project.
Packing and Preservation
- Corrosion prevention and packaging shall be in accordance with the minimum requirements as stated in this specification.
- However the responsibility remains with the Vendor to apply equal or more suitable protection and / or packing to ensure safe arrival of the gaskets at their ultimate destination.
- Each gasket shall be free from sharp edges, burrs, organic substances (e.g. grease, oil, lubricants, sealants and preservatives), rust, dirt or any other foreign particulate matter.
- The filler material shall be free from blisters, crack or other surface imperfections e.g. porosity, voids, inclusions or other defects which could impair satisfactory performance.
- Gaskets shall be packed in such a manner so as to avoid damage or atmospheric corrosion to inside or outside surfaces or parts, during storage or while in transit.