Aircraft Navigation (Obstruction Aids)

Where required aircraft navigation obstruction lights complete with all necessary cabling, control equipment, solar panels, storage batteries, access ladders and platforms shall be fitted.

All installation shall be in accordance with approved general arrangement drawings and supplier's instructions.

8.7 QUALITY CONTROL 8.7.1 General

Routine tests on raw material and fabricated individual members (components) of lattice steel towers and associated steelwork shall be undertaken in accordance with the requirements of this Specification.

Prototype (type) tests on lattice steel towers shall be undertaken when required by the Engineer in accordance with the requirements of Clause 8.7.7.

All steel ex-mills or received from merchants' stocks shall be marked to identify the cast or casts from which it was made in accordance with Section 9 of BS EN 10025 and Section 10 of BS EN 10210, and be covered by a test (mill) certificate stating the mechanical, chemical and where specified the impact properties and carbon equivalent value and clearly showing the cast numbers; to prove compliance with tables 2 and 5 of BS EN 10025 and tables Al and A3 of BS EN 10210.

The optional impact test BS EN 10210 option 1.6 for quality JO steel hollow sections is required.

Unless agreed to the contrary the following maximum Carbon Equivalent Values (CEV) for steel supplied in accordance with BS EN 10025 and BS EN 10210 shall not be exceeded:

Grade S235 0.35

S275 0.41 S355 0.45 see also BS 5950 Part 2, Clause 4.2

All high tensile steel solid round sections shall be ultrasonic tested for laminations at the rolling mills in accordance with the requirements of BS 5996.

In the event of test certificates being unobtainable, the Contractor shall arrange, at his own cost, for the independent testing and analysis of materials. Testing shall be in accordance with the requirements of BS EN 10025, Section 8 and BS EN 10210, Section 7.

The material grades of all individual pieces of shall be capable of positive identification at all stages of fabrication.

Steels of different quality shall be stored separately.

Bolts and nuts shall be covered by the appropriate test certificate in respect of the tests requirements stated in BS 4190.

Copies of all test certificates shall be made available to the Engineer.

8.7.2 Welding

Unless specified to the contrary all structural welded joints shall be undertaken using approved welding procedures in accordance with BS EN 288.

Copies of the welding procedures shall be made available to the Engineer upon request. However, for all welding associated with the fabrication of high tensile steel solid round sections, or where the combined thickness of the material is in excess of 60 mm, the welding procedures shall be submitted to the Engineer for approval, together with the related quality control documentation such as electrode storage, drying and handling requirements. This is a Hold Point.

All welders shall be tested to meet the requirements of BS EN 287 Part 1 using the appropriate test corresponding to the weld positions and parent materials to be used. Copies of the test certificates shall be made available to the Engineer upon request.

The Engineer reserves the right to have any welding operator retested at any time at no extra cost.

Unless specified to the contrary all welding shall be subjected to a non-destructive testing (NDT) programme. Where necessary, this may involve the appointment by the supplier of an independent NDT organization approved by the Engineer who will undertake the NDT programme. This is a Hold Point.

The NDT organization shall have operators suitably qualified to Level 2 of PCN/WSB/MT/001/87. The NDT organization shall submit their proposed procedures for approval. This is a Hold Point. The Contractor shall then ensure that the approved procedures are rigidly adhered to.

The Contractor shall arrange for the appropriate level of weld/inspection to be undertaken, which shall not be less than the following minimum requirements. For details of the required level of inspection reference should be made to Appendix 8.A9.

Level 1: 100 percent visual inspections in accordance with the requirements of BS 5289.

Level 2: 10 percent of the overall output shall be magnetic particle tested to the acceptance criteria stated in BS 5135 Tables 18 and 19, Category C (except for porosity, see Note A) for butt and fillet welds respectively.

Level 3: 10 percent of each welder's output shall be magnetic particle tested to the acceptance criteria stated in BS 5135 Tables 18 and 19, Category B (except for porosity, see Note A) for butt and fillet welds respectively.

Level 4: 20 percent of each welder's output shall be magnetic particle tested to the acceptance criteria stated in BS 5135 Tables 19, Category B (except for porosity, see Note A) for fillet welds.

Level 5: 10 percent of each welder's output shall be ultrasonic tested, with a further 10 percent of each welder's output magnetic particle tested - both to the acceptance criteria in BS 5135, Table 18, Category B except for porosity, see Note A) for butt welds.

Note: A All welds, especially butt welds must be continuous to ensure a pickle-tight connection when galvanised.

B Ultrasonic testing to be in accordance with BS 3923, Part: 1.

C Magnetic particle testing to be in accordance with BS 6072.

All weld inspection/testing, shall be undertaken a minimum of 48 hours after the completion of the respective weld. This is a Notification point.

Copies of the NDT inspection reports for weld inspection levels 5 and 4 shall be made available to the Employer.

Copies for the NDT inspection reports for weld inspection level 3 and 2 shall be made available to the Employer upon request.

8.7.3 Castings

All malleable cast iron castings shall be thoroughly inspected after sand blasting and any casting with castings defects e.g. sand inclusions and metal penetrations, cracking, raised core, porosity shall be scrapped.