Section 6 Steel used in repairs

6.1.1 When renewals are required, Surveyors should ensure that the grade of steel to be used in the repair is in accordance with, or equivalent to, the grades listed on the approved plans.

6.1.2 Steel used for repair of classed ships should be manufactured, tested and certified in accordance with the requirements of the Rules for Materials.

6.1.3 Limited quantities of steel complying with the requirements of a national or proprietary specification may be accepted subject to the following conditions:

1. The material is considered equivalent to the minimum requirements of the steel grade shown on the plan.

2. The manufacturer is approved by LR to supply the grade of steel shown on the plan.

3. The identity stamped on the material and the material condition clearly conform to the details shown on the certificate.

4. Representative samples selected for check mechanical and chemical analysis tests are satisfactory.

5. Copies of the manufacturer’s test certificate and the results from the check tests are recorded.

6.1.4 For guidance, the term limited quantities is defined as up to 5 tonnes of plate and up to 2 tonnes of sections. Equivalent LR, Naval and International steel grades are given in Table 15.6.1 Rolled plate and sections, material grade equivalence and Table 15.6.2 Material and welding standard equivalence. Where no real equivalent grade exists, the next highest grade should be used.

6.1.5 When it is not possible to carry out check tests before the repair is completed, a sample should be retained for subsequent testing before departure of the vessel. However, every effort should be made to ensure that the material is tested before the repair is completed. The repair is to be considered as incomplete, until such tests have been carried out and the results confirmed as satisfactory.

6.1.6 Defects in steel to be used for repairs are to be addressed in accordance with the requirements of Ch 3, 2.3 Defects in steel products.

6.1.7 For the purpose of scantling calculation Admiralty long stalk tee bar dimensions are given in Figure 15.6.1 Standard T bar sections and Table 15.6.3 Admiralty long stalk tee bar sections.

6.1.8 Due to the limited availability of Admiralty long stalk tee bars, alternative sections may be used. Suitable alternative sections are given in Table 15.6.4 Alternatives to Admiralty long stalk tee bars. For large scale replacement IPN beams should be used in preference to fabricated tee bars. Where alternative sections are used, care is to be taken to ensure a smooth transition, using a 1 in 4 taper, between different sections. Additional flat bar pieces of a depth not less than the flange thickness and extending two times the web depth from the connection, may be necessary to maintain the continuity of section modulus where the changes in flange width or thickness between sections is large.