ASTM D1838 Test Method for Copper Strip Corrosion by Liquefied Petroleum (LP) Gases
6. Apparatus
6.1 Corrosion Test Cylinder, constructed of stainless steel with an O-ring removable top closure according to the dimensions given in Fig. 1. Provide a flexible inert hose, such as one composed of aluminum or stainless steel, which permits inverting the test cylinder as required in the procedure (see 6.1.1). The whole assembly, including the corrosion test cylinder, shall be constructed to withstand a minimum hydrostatic test pressure of 6900 kPa (1000 psig). No leak shall be discernible when tested at 3450 kPa (500 psig) with gas.
6.1.1 Swivel connections with an adapter to fit a 6.4 mm (1/4 in.) pipe may be used.
6.1.2 The assembly shall be tested for compliance with the minimum pressure rating of 6900 kPa (1000 psig) by hydrostatic testing, or alternative testing protocol acceptable to the local authority having jurisdiction, prior to first use. Additional testing can be required by the local authority having jurisdiction.
6.1.3 The assembly shall be verified for gas tightness by leak testing at a minimum of 3450 kPa (500 psig) with inert gas prior to first use, whenever pressure-containing components of the assembly are replaced, or otherwise on an annual basis.
6.1.4 Note the presence and length (about 60 mm) of the outage tube shown in Fig. 1, to provide adequate ullage for safety. A safety pressure relief device may also be incorporated into the design of the corrosion test cylinder, if desired. If a pressure relief device is incorporated, ensure that the materials of its construction will not affect the test results.
6.2 Water Bath, capable of being maintained at 37.8 °C +/- 0.5 °C (100 °F +/- 1 °F). Incorporate suitable supports to hold the test cylinder in an upright position. Make the bath deep enough so that the entire cylinder and valves will be covered during the test.
6.3 Temperature Sensing Device (TSD) - Capable of monitoring the desired test temperature in the bath to within an accuracy of +/- 0.5 °C (1 °F) or better.
6.4 Strip Polishing Vise, to hold the copper strip firmly without marring the edges. For convenient vises see Test Method D130.
7. Materials
7.1 Wash Solvent - Any volatile, less than 5 mg/kg sulfur, hydrocarbon solvent may be used provided that it shows no tarnish at all when tested for 3 h at 50 °C (122 °F). 2,2,4-trimethylpentane (isooctane) of minimum 99.75 % purity is the referee solvent and should be used in case of dispute. (Warning - Extremely flammable, see Annex A1.)
7.2 Copper Strip Specification - Use strips that are 12.5 mm +/- 2 mm (1/2 in.) wide, 1.5 mm to 3.2 mm (1/16 to 1/8 in.) thick, and cut 75 mm +/- 5 mm (3 in.) long from smooth-surfaced, hard-temper, cold-finished copper of 99.9+ % purity; electrical bus bar stock is generally suitable. Drill a 3.2 mm (1/8 in.) hole approximately 3.2 mm (1/8 in.) from one end in the center of the strip. The strips may be used repeatedly but shall be discarded when the strip's surface shows pitting or deep scratches that cannot be removed by the specified polishing procedure, or when the surface becomes deformed, or the dimensions for the copper strip fall outside the specified limits.
7.3 Surface Preparation/Polishing Materials - 00 grade or finer steel wool; silicon carbide grit paper or cloth of varying degrees of fineness including 65-µm grade (220-grit CAMI-grade or P220 FEPA-grade); also a supply of 105-µm (120-grit to 150-grit CAMI-grade or P120 to P150 FEPA-grade) size silicon carbide grain or powder and absorbent cotton. A commercial grade is suitable, but pharmaceutical grade cotton wool is most commonly available and is acceptable.
7.4 ASTM Copper Strip Corrosion Standard (ADJD0130), Plaques are available. Their care and inspection for stability are described in detail in Test Method D130.
