This specification covers rubber rings used as seals for asbestos-cement pipe joints. Material under this specification consists of natural or synthetic rubber rings, or both, for use in applications requiring non-oil resistant rings, and synthetic rubber rings for use in applications requiring oil-resistant rings. The ring shall be manufactured from a properly vulcanized virgin rubber compound, that is, rubber containing no scrap, reclaim, or rubber substitutes, with dimensions that shall conform to the requirements specified. The ring must also possess a surface that is smooth and free of pitting, cracks, blisters, air marks, and other imperfections, and a body free of porosity and air pockets. Tests for tensile strength, elongation, stress at elongation, hardness, compression set, low-temperature flexibility, volume change, and appearance change shall be performed and shall conform to the requirements specified.

1.1 This specification covers rubber rings used to seal the joints of asbestos-cement pipe conforming to Specifications C 296, C 428, C 644, and C 668.

1.2 A specification is given for ( 1) natural or synthetic rubber rings, or both, where resistance to oil or solvents is not required, and (2) synthetic rubber rings for services involving resistance to oil or solvents.

1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.4 Breathing of asbestos dust is hazardous. Asbestos and asbestos products present demonstrated health risks for users and for those with whom they come into contact. In addition to other precautions, when working with asbestos-cement products, minimize the dust that results. For information on the safe use of chrysotile asbestos, refer to "Safe Use of Chrysotile: A Manual on Preventive and Control Measures."

The following safety hazards caveat pertains only to the test methods portion, Section , of this standard: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.