Section 6 Manufacture, Workmanship and Testing

601. General

1. The manufacture, testing, inspection and documentation are to be in accordance with recognized standards and the specific requirements given in the Guidance.

2. For gas related equipment, the manufacture, testing and inspection not specified in this section are to be in accordance with relevant requirements in Pt.7, Ch.5 of the Rules for Steel Ships.

602. Gas tanks

Tests related to welding and tank testing are to be in accordance with Pt.7, Ch. 5, 410. and 411. of the Rules for Steel Ships.

603. Gas piping systems

1. The requirements for testing are to apply to gas piping inside and outside the gas tanks. However, relaxation from these requirements may be accepted for piping inside gas tanks and open-ended piping.

2. Welding procedure tests are to be required for gas piping and are to be similar to those required for gas tanks in the Pt.7, Ch.5, 603. 3 of the Rules for Steel Ships. Unless otherwise especially agreed with the Society, the test requirements are to be in accordance with para. 3 below.

3. Test requirements

(1) Tensile tests : Generally, tensile strength is not to be less than the specified minimum tensile strength for the appropriate parent materials. The Society may also require that the transverse weld tensile strength is not to be less than the specified tensile strength for the weld metal, where the weld metal has a lower tensile strength than that of the parent metal. In every case,

the position of fracture is to

(2) Bend tests : No fracture is

be reported for information.

to be acceptable after a 180° bend over a former of a diameter

four times the thickness of the test piece, unless otherwise specially required or agreed Society.

with the

(3) Charpy V-notch impact tests : Charpy tests are to be conducted at the temperature prescribed for the base material being joined. The results of the weld impact tests, minimum average en- ergy (E), is to be no less than 27 J. The weld metal requirements for sub-size specimens and singe energy values are to be in accordance with Pt.7 Ch.5, 601. 4 of the Rules for Steel Ships. The results of fusion line and heat affected zone impact tests are to show a minimum average energy (E) in accordance with the transverse or longitudinal requirements of the base material, whichever applicable, and for sub-size specimens, the minimum average energy (E) is to be in accordance with Pt.7 Ch.5, 601. 4 of the Rules for Steel Ships. If the material thick- ness does not permit machining either full-sized or standard sub-size specimens, the testing pro- cedure and acceptance standards are to in accordance with recognized standards. Impact testing is not required for piping with thickness less than 6 mm.

4. In addition to normal controls before and during the welding and to the visual inspection of the finished welds, the following tests are to be required :

(1) For butt welded joints for piping systems with design temperatures lower than -10 °C and with

(2)

inside diameters of more than 75 mm or wall thicknesses graphic testing is to be required.

When such butt welded joints of piping sections are made

the pipe fabrication shop, upon special approval, the extent

greater than 10 mm, 100% radio-

by automatic welding processes in of radiographic inspection may be

(3)

(4)

(5)

progressively reduced but in no case to less than 10% of the joints. If defects are revealed, the

extent of examination is to be increased to 100% and shall include inspection of previously ac- cepted welds. This special approval is only to be granted if well-documented quality assurance procedures and records are available to enable the Society to assess the ability of the manu- facturer to produce satisfactory welds consistently.

For other butt welded joints of pipes, spot radiographic tests or other non-destructive tests are to be carried out at the discretion of the Society depending upon service, position and materials.

In general, at least 10% of butt welded joints of pipes is to be radio- graphed.

Butt welded joints of high-pressure gas pipes and gas supply pipes in ESD-protected machinery spaces are to be subjected to 100% radio-graphic testing.

The radiographs are to be assessed according to a recognized standard(Refer to ISO 5817:2003, Arc- welded joints in steel-Guidance on quality levels for imperfections, and are to at least meet the requirements for quality level B).

5. After assembly, all gas piping are to be subjected to a hydrostatic test to at least 1.5 times the de- sign pressure. However, when piping systems or parts of systems are completely manufactured and equipped with all fittings, the hydrostatic test may be conducted prior to installation aboard ship. Joints welded on board are to be hydrostatically tested to at least 1.5 times the design pressure. Where water cannot be tolerated and the piping cannot be dried prior to putting the system into service, proposals for alternative testing fluids or testing methods are to be submitted for approval.

6. After assembly on board, each gas piping system is to be subjected to a leak test using air, halides or other suitable medium.

7. All gas piping systems including valves, fittings and associated equipment for handling gas are to be tested under normal operating condition before set into normal operation.

604. Ducting

If the gas piping duct contains high-pressure pipes the ducting is to be pressure tested to at least

1.0 MPa.

605. Valves

1. Type tests

Each size and type of valve intended to be used at a working temperature below -55 °C is to be type approved. Type tests to the minimum design temperature or lower and to a pressure not lower than the maximum design pressure foreseen for the valves is to be witnessed in the presence of

the Surveyor.

Type tests are to include hydrostatic test of the valve body at a pressure equal to

1.5 times the design pressure, seat and stem leakage test at a pressure equal to 1.1 times the de-

sign pressure,

and cryogenic testing consisting of valve operation and leakage verification at the de-

sign temperature.

For valves intended to be used at a working temperature above -55 °C, type approval is not

required.

2. Production tests

All valves used in gas piping systems are to be tested at the plant of manufacturer in the presence of the Surveyor. Testing is to include hydrostatic test of the valve body at a pressure equal to 1.5 times the design pressure, seat and stem leakage test at a pressure equal to 1.1 times the design pressure.

In addition, cryogenic testing consisting of valve operation and leakage verification at the design temperature for a minimum of 10% of each type and size of valve for valves intended to be used at a working temperature below -55 °C.

As an alternative to the above, the manufacturer may request the Society to certify a valve subject to the following:

(1) The valve has been type approved as required by Par. 1 for valves intended to be used at a working temperature below -55 °C, and

(2) The manufacturer has a recognized quality system that has been assessed and certified by the

Society subject to periodic audits, and

(3) The quality control plan contains a provision to subject each valve to a hydrostatic test of the

valve body at a pressure equal to 1.5 times the design pressure and seat and stem leakage test at a pressure equal to 1.1 times the design pressure. The manufacturer is to maintain records of such tests, and

(4) Cryogenic testing consisting of valve operation and leakage verification at the design temper- ature for a minimum of 10 % of each type and size of valve for valves intended to be used at

606. Expansion bellows

1. Each type of expansion bellows intended for use in gas piping, primarily on those used outside the gas tank are to be type approved by the following test.

(1) An overpressure test. A type element of the bellows, not pre-compressed, is to be pressure test- ed to a pressure not less than 5 times the design pressure without bursting. The duration of the test is not to be less than 5 min.

(2) A pressure test on a type expansion joint complete with all the accessories (flanges, stays, ar- ticulations, etc.) at twice the design pressure at the extreme displacement conditions recom- mended by the manufacturer. No permanent deformations is to be allowed. Depending on mate-

rials the test may be required to be performed at the minimum design temperature.

(3)

(4)

A cyclic test (thermal movements). The test is to be performed on a complete expansion joint, which is to successfully withstand at least as many cycles, under the conditions of pressure, temperature, axial movement, rotational movement and transverse movement, as it will encounter in actual service. Testing at room temperature, when conservative, is permitted.

A cyclic fatigue test (ship deformation) should be performed on a complete expansion joint, without internal pressure, by simulating the bellows movement corresponding to a compensated pipe length, for at least 2,000,000 cycles at a frequency not higher than 5 cyclesÕs. This test is only required when, due to the piping arrangement, ship deformation loads are actually experienced.

2.

607.

1.

The Society may waive performance of the tests specified in par.1 provided that complete doc- umentation is supplied to establish the suitability of the expansion joints to withstand the expected working conditions. When the maximum internal pressure exceeds 0.1 MPa gauge this doc- umentation is to include sufficient test data to justify the design method used, with particular refer- ence to correlation between calculation and test results.

Gas fuel pumps

Each size and type of pumps is subject to drawing approval and the tests of following (1) to (3) in the presence of the Surveyor. However, for the pump designed the same as an existing pump approved by the Society and having satisfactory in-service experience, consideration may be given to waiving the tests.

(1) hydrostatic test of the pump body equal to 1.5 times the design pressure

(2) the following capacity tests

(A) For submerged pumps, the capacity test is to be carried out with the design medium or

with a medium below the design temperature.

(B) For deep well pumps, the capacity test may be carried out with water. In addition, for deep well pumps, a spin test to demonstrate satisfactory operation of bearing clearances, wear rings and sealing arrangements is to be carried out at the design temperature.

(3) After completion of tests, the pump is to be opened out for examination

2. All pumps of the same size and type which have been granted drawing approval are subject to the tests of following (1) and (2) at the plant of manufacturer in the presence of the Surveyor.

(1) hydrostatic test of the pump body equal to 1.5 times the design pressure

(2) the following capacity tests;

(A) For submerged pumps, the capacity test is to be carried out with the design medium or with a medium below the design temperature.

(B) For deep well pumps, the capacity test may be carried out with water.

The manufacturer may request the Society to waive the above tests subject to the follow- ing:

(3) The pump has been tested as required by par. 1 and

(4) The manufacturer has a recognised quality system that has been assessed and certified by the

Society subject to periodic audits, and

(5) The quality control plan contains a provision to subject each pump to a hydrostatic test of the pump body equal to 1.5 times the design pressure and a capacity test. The manufacturer is to

maintain records of such tests.