1. The length and dimension of Curve Bolt must be matched to the approved R.C Segment.
2. The model of Curve Bolt (Drw. No. XMSCBS-TK-58-30) designed by Thaitoke Engineering Co., Ltd is not identified the dimension which appears in the Curve Bolt & Straight Bolt Typical Detail model. Instead it was identified length and screw pitch. As required, being approved, the obvious dimension is required to identify in the model.
3. The Straight Bolt size in the Drw. No. M24-TK-58-060 is Rodɸ21.6/21.67mm but ɸ screw size is 24 mm which is not correct. Also the model has to be identified the Grade of Bolt type and Bolt Head Marketing details.
4. The screw pitch and Curve Bolt length must be designed to fit the other accessories for instance, Gromments, Washers and Nuts and also the pitch of Bituminous Gasket which affects the length of Curve Bolt. Mis-determination of Curve Bolt length would evoke the damage as we have mass production.
5. Bolt for RC Segment shall be tightened to a minimum torque of 16 kg-m or directed by the engineer ; as appendix of tunnel design page 184.
6. Curve Bolt was not identified dimension and also the Chemical Composition & Mechanical Properties unlike Straight Bolt.
7. Rust-proof immerse details of Bolts, Nut & Washer was not identified in model.
8. Grout Hole Pullout test must not less than 5 times of the heaviest tunnel element.
9. Qualification and size of EC Segment Bolts must be matched to RC segment design both diameter and qualification (Grade of Segment Bolt, Nut & Washer).
10. Grout Socket O-Ring must have a leak and should set Max. Torque which used to prevent cracking or damage Grout Cap. The leakage testing of the Grout cap seal is also required.
11. Defining test materials were produced for each category Bolts Inertia Proving that the materials used in the manufacture or Mill sheet of material used in the production of Bolt Grade 8.8 & 5.8.
12. The manufacturer should determine the quality of the products that have the quality by doing random checks.