Purchase order for Nuts and Bolts include Bill of Material as well as Technical Requirements for Nuts and Bolts. Sample Technical Requirements for a particular project is as shown below:
Length and Diameter of Bolts
- 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.
- 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.
- All nuts shall be of heavy hexagonal type and shall be in accordance with ASME B18.2, except where modified by this specification.
- 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.
|All||150# to 900#||≥ 2″|
|All||1500# and above||≥ 1 1/2″|
Negative tolerance is not permitted on the length of the bolting.
Inspection and Testing
- Fasteners 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 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 in accordance with the PMI standards/specifications applicable to the project.
Product Marking and Color Coding
- 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.
- 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 at their ultimate destination.
- Bolting items shall be supplied with suitable rust preventive.
- Fasteners 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.