Relief_valve_overhaul_spec_modified.docx

WORK ITEM 1: Relief Valves, Overhaul

1. SCOPE

1.1 Intent. This work item describes the requirements for the Contractor to renew or overhaul the relief valves listed in Table 1.

1.2 Government-furnished property.

None.

2. REFERENCES

COAST GUARD DRAWINGS

Coast Guard Drawing 750-WMSL-100-060, Rev C, General Arrangements NSC 3 Only

(AS3100001)

Coast Guard Drawing 750-WMSL-801-004, Rev A, Booklet of General Plans NSC 3 SRD

(ASC801001C)

Coast Guard Drawing 750-WMSL-505-001, Rev C, List of Relief Valves (ASC505001)

COAST GUARD PUBLICATIONS

Coast Guard Technical Publication (TP) 7087, 04-OCT-07, Pressure Relief Valve Commandant Instruction M10360.3C (COMDTINST M10360.3C), 11 Mar 2005, Coatings and Color Manual

Surface Forces Logistics Center Standard Specification (SFLC Std Spec) 0000, Jan 2014, General Requirements

Surface Forces Logistics Center Standard Specification 6310 (SFLC Std Spec 6310), 2014, Requirements for Preservation of Ship Structures

OTHER REFERENCES

None.

3. REQUIREMENTS

3.1 General.

3.1.2 Protective measures. The Contractor shall furnish and install all protective coverings to seal off and protect all non-affected vessel's components, equipment, and spaces near the work area against contamination during the performance of work. Upon completion of work, the Contractor shall remove all installed protective measures, inspect for the presence of contamination, and return all contaminated equipment, components, and spaces to original condition of cleanliness.

3.1.3 Interferences. The Contractor shall handle all interferences in accordance with SFLC Std Spec 0000, paragraph 3.3.5 (Interferences). Known interferences include, but are not limited to the following:

a. Piping systems

b. Insulation

3.2 Relief valve test. The Contractor shall test the relief valves listed in Table 1.

Table 1. List of Relief valves

3.3 Valve removal and tagging. Prior to removal, the Contractor shall identify and tag all valves listed in Table 1 with location and service, system working pressure, and relief pressure. The Coast Guard Inspector shall assist in locating the valves.

3.3.1 The Contractor shall ensure that, in accordance with Std Spec 0000, the relief valve is isolated, isolation valves tagged, and pressure is relieved prior to removal.

3.3.2 Disconnect any interferences and necessary piping, and remove the valves. Install blank flanges with gaskets over the pipe openings, securing with at least four bolts, 90 degrees apart. Pipe plugs or other closures may be used to prevent contamination of the system, depending on the valve removed. Blank flanges shall be at least ¼" thick.

3.4 Valve testing. In the presence of Coast Guard Inspector, the Contractor shall shop test and set each new and overhauled valve to the correct lifting pressure. Using clean fresh water as a test medium (if water is not detrimental to the valve components, otherwise utilize the system fluid or other suitable medium), simulate system temperature and pressure, and bring the test pressure to 10 psi below the relief or safety valve operating pressure. Slowly raise the test pressure to the set relief or safety pressure setting, and record the pressure where the valve provides relief or the safety valve lifts. Submit a CFR.

3.4.1 Provide the Coast Guard Inspector with CFR documenting the test pressure and relief pressure (lifting pressure) for each valve. Affix a metal tag, using lock wire, to each valve showing the following information:

a. Ship name and hull number

b. Valve number or identification

c. Valve lifting pressure

d. Date valve tested and set

e. Name and location of repair facility (Contractor).

f. Install new Label Plate in accordance with Para 3.3.13 of SFLC Std Spec 0000.

Label plate information must be professionally marked (engraved). Hand written label plate is not acceptable.

NOTE

Any of the valves listed in Table 1 may be renewed or overhauled based on the test results. A CFR shall be submitted to the Coast Guard stating the condition and test results substantiating the need for overhaul or renewal. Coast Guard will make a final decision whether a valve will be renewed or overhauled and notify contractor via CFRR and/or Change Request.

3.5 Valve overhaul.

When directed by the Coast Guard, the Contractor shall overhaul, pressure test, and set each valve to the lifting set point pressure indicated in the Table 1.

3.5.1 Inspect all valve openings for obstructions and damage to the valve seat, disc, and body.

3.5.2 Clean all valves of foreign matter including, but not limited to, dirt, scale, rust, grease, and marine growth. Clean valve discs and seats to bright metal without injuring parts.

3.5.3 Check valve stems for trueness and realign them as necessary. Straighten stem to within 0.002 inch of total indicator reading, as required. Polish stem to a 32 RMS finish and remove raised edges and foreign matter.

3.5.4 Machine, grind-in, or lap and spot-in metallic disc to seat to obtain a 360 degree continuous contact between the disc and seat. If additional work is required to achieve a continuous seat, such as building up by welding, submit a CFR. Verify proper valve seating by spotting-in with Prussian blue in the presence of the Coast Guard Inspector.

3.5.5 Clean, chase, and tap valve stem threads and exposed threaded areas.

3.5.6 Dress and true gasket mating surfaces.

3.5.7 Reassemble all overhauled valves. Remove all packing and renew it in kind with new packing of the same size and type as that removed.

3.5.8 Renew seals, gaskets, packing, and disc nuts in kind and in accordance with manufacturer's specifications.

3.6 Valve renewal. If a Change Request has been authorized, renew designated relief valves with MSS commercial-standard type valves. New valves shall be equivalent (including identical material) to the valve being renewed.

3.7 Valve preservation. Contractor is required to follow the color coding guidelines outlined in COMDTINST M10360.3.

3.8 Valve reinstallation. Upon completion of shop work, clean hardware, remove blank flanges, pipe plugs, etc. and clean, dress, and true gasket mating surfaces. Install the relief valves along with any removed piping or interferences in the presence of the Coast Guard Inspector. Renew gaskets and seals to match the original.

3.9 Leak test – post installation. After all authorized repairs of mechanical (i.e. threaded, bolted, etc.) joints, the Contractor (in the presence of a Coast Guard Inspector) shall perform an operational test of the affected system using the system fluid at normal operating pressure. No leakage is acceptable. Repair all leaks and discrepancies found. Submit a CFR.

3.10 Flange shields. Provide and install new flange spray shields on all flange connections which serve flammable liquids to match the original configuration.

3.11 Touch-up preservation. The Contractor shall prepare and coat all new and disturbed surfaces to match existing adjacent surfaces in accordance with SFLC Std Spec 6310, paragraph 3.1.13 (Touch-ups and minor coating repairs.)