1. Purpose
1.1 This specification defines requirements for the skid fabricator in addtion to requirements found in specification 4AEL-620300.
2. SCOPE
2.1 See 4AEL-620300 for general scope.
2.2 This document must be used in conjunction with specification 4AEL-620300. All section numbers in this document are identical and modifications shown here supersede or replace the specific section in 4AEL-620300. Skid fabricator is responsible for all items referring to contractor in specification 4AEL-620300.
3. RELATED DOCUMENTS
3.1 Air Products Engineering Documents
4AEL-620300 Electrical Work
4. MATERIALS AND EQUIPMENT
4.1 See 4AEL-620300 for general requirements. Conduit seal fittings shall not be poured by the skid fabricator. The field contractor will pour seals after circuit checkout.
4.2 A skid’s base metal frame shall be equipped with NEMA 2-hole grounding pads, one pad welded into each corner on the long side of the skid for a total of 4 ground pads.
4.2.1 All electrical enclosures, motors, lighting fixtures, and electrical equipment mounted on the skid shall be tied to a common grounding point on the skid which will allow for connection to the overall electrical ground system when the skid is installed in the field. Any special grounding instructions will be indicated on design drawings.
5. INSTALLATION PROCEDURES (See 4AEL-620300)
6. WELDING ON SKIDS
6.1 This section replaces Section 6 in 4AEL-620300.
6.2 Grounding of welding machines shall be achieved as directly as possible using adequate cable connected to a proven low resistance ground. The skid fabricator’s shop metal structure, the power company ground, or a driven ground rod are satisfactory only when proven to have continuity to all other grounding elements within the immediate vicinity.
6.2.1 The ground or return cable of a welder shall be connected to the work piece with as little distance as possible between the cable connection and the work piece being welded.
6.3 When welding is required on a skid after a Programmable Electronic System (PES) has been placed on a skid, all personnel must be informed of the possible danger to the equipment and themselves. Welding cables shall not be placed near cables at the DCS, PLC, or other electronic devices. Operation of the DCS, PLC, or other electronic control devices shall be suspended until all welding activity has been completed.
- INSPECTION AND TESTING (See 4AEL-620300)
7.2.4 Does not apply.
7.2.5 Does not apply.
7.2.7 Does not apply.
7.2.10 Does not apply.
7.2.12 Does not apply.
7.2.14 Does not apply.
7.2.15 Does not apply.
7.2.20 Perform dc insulation resistance test on each high-voltage bus and motor control center bus: phase-to-phase and phase-to-ground. Perform contact resistance test on each complete high voltage bus and motor control center bus. Test value shall be 30 micro-ohms per joint or less.
7.2.21 When provided on a skid, electronic equipment such as a PES may require system checkout at the skid fabrication shop during construction. Air Products will make arrangements as necessary with the skid vendor outlining requirements and schedule for this testing.
7.2.22 During the PES checkout period, it is preferred that no electric arc welding be performed on the skid. If welding must be performed, it is extremely important that the welder ground cable is not connected to, or come in contact with, the control system ground.
7.3 User Tests—Air Products may be performing user tests on skided equipment. See contract documentation for additional information on requirements.