Requirements for Fasteners
- The diameters and lengths of stud bolts shall conform to standards ASME B16.5 (for flanges 24” and smaller), ASME B16.47 Series A/MSS SP 44 (for flanges 26” and larger) and ASME B18.2.1.
- For stud bolts the diameter shall be specified in inches and lengths in millimeters.
- All nuts shall be of heavy hexagonal type and shall be in accordance with ASME B18.2, except where modified by this specification.
- Stud bolt lengths shall be the effective thread length excluding the end points, in accordance with ASME B16.5. The lengths mentioned in the requisition are service lengths that do not include the dimensions of the end bevel.
- If the nuts of grade 4 or 7M are specified in the material requisition, then the supplementary requirements S3 specified in ASTM A194 shall apply. Impact test temperature and test values shall be as per A 320 respective grade.
- All Fasteners specified for sour service shall meet the requirements of NACE MR0175/ISO 15156 – latest edition.
- Where specified bolting shall be galvanized in accordance with ISO 1461. Thread fits shall be class 2A for bolts and class 2B for nuts after galvanizing.
- Vendor shall propose measures if any to be taken to prevent the risk of galling between high alloys bolts and nuts.
- For stud bolts, jackscrews and nuts, the threading shall conform to the following series of standard ASME B1.1.
- “Coarse” series: for bolt diameters less than or equal to 1”
- “8 threads” series: for bolt diameters equal to or greater than 1⅛”
- Stud bolts shall be threaded along their entire length. The machining and surface condition tolerances applicable to the various threading shall conform to the following classes:
- Class 2A of standard ASME B1.1 for stud bolts and screws
- Class 2B of standard ASME B1.1 for nuts
- Unless otherwise specified, hydraulic bolt tensioning shall be applied as given in the table below. For such instances, the bolt lengths specified in the Inquiry / Purchase Requisition includes additional length (minimum one bolt diameter) and the bolts shall be supplied with 3 nuts.
150# to 900#
1500# and above
≥ 1 1/2″
- Bolting items shall be supplied with a suitable rust preventive (e.g. Shell Ensis Fluid or equal).
- Negative tolerance is not permitted on the length of the bolting.
- In addition to the marking requirements of the relevant product codes and standards, the stock code number, purchase order number and purchase order item number shall be printed on each box or package.
Requirements for Gaskets
- Gaskets shall conform to the following standard, except where modified by this specification.ASME B16.20 for spiral wound and ring type gaskets.ASME B16.21 for flat ring gaskets.
- 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”.
- 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.
- Asbestos shall not be used for non-metallic gaskets or part of metallic gaskets. Use of asbestos in any form is strictly prohibited.
- 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 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.
- Flange gasket contact surface finish shall be in accordance with ASME B16.5.
- 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
- 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.
- In addition to the marking requirements of the relevant product codes and standards, the stock code number, Purchase Order number and Purchase Order item number shall be marked on each package.
- All Gaskets specified for sour service shall meet the requirements of NACE MR0175/ ISO 15156 – latest edition.
- All spiral wound gaskets in class 150 shall be of low density (low stress) type which are designed to seat at lower bolt loads.
Requirements for Insulating Gasket Kits
- Insulating gasket kits shall be to manufacturers standard, with each kit comprising of:
- 3mm thick flat ring insulating
- gasket to ASME B16.21, material shall be Neoprene reinforced Phenolic/manufacturer’s standard material.
- Full length insulating sleeves (1 sleeve per bolt); material shall be Polyethelene/Phenolic/Mylar/manufacturer’s standard material.
- Insulating washers 3mm thick (2 washers per bolt), material shall be Reinforced Phenolic material
- Steel back-up washers 3mm thick (2 washers per bolt).
- Insulating gasket kit (including bolt sleeves and washers) material should be of high insulating quality that should, in addition to protecting flanges from corrosion, meet the pressure/temperature requirements of the system.
- The bore of the insulating gasket should be equal to the pipe bore. This will prevent any service material from accumulating in the annular space between the bore of the gasket and the bore of the pipe thus preventing formation of electrical bridge.
- Insulating gasket should be suitable for the intended flange class, the maximum pressure and temperature conditions of system and service fluid.
Inspection and Testing
- Fasteners and 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.
- Fasteners and 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.
- Fasteners which are specified as for low temperature service shall be impact tested as specified in the Material Requisition.
- Positive Material Identification (PMI) shall be conducted for all SS / DSS / CRA alloy fasteners and gaskets in accordance with the PMI standards/specifications applicable to the project.
Marking and Colour 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 fasteners and 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.
- Bolting items shall be supplied with suitable rust preventive.
- Fasteners and 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. All bolting shall be supplied assembled with nuts.