This specification covers cylindrical tanks fabricated by contact molding for above-ground vertical installation, to contain aggressive chemicals at essentially atmospheric pressure, and made of a commercial-grade polyester or vinyl ester, resin. This specification does not cover the design of vessels intended for pressure above hydrostatic, vacuum conditions, except as classified herein, or vessels intended for use with liquids heated above their flash points. The tanks are classified as type I and II according to the operating pressure or vacuum levels, and the safety factor required for external pressure. The tanks are further classified as grade 1 and 2 according to the generic types of thermoset resin. The resin used shall be a commercial grade, corrosion-resistant thermoset. The reinforcement should be a chopped-strand mat, a nonwoven biaxial or unidirectal fabric, a woven roving, or a surface mat. Materials shall be tested and the individual grades shall conform to specified values of design requirements such as straight shell, external pressure, top head, bottom head, open-top tanks, joints, fittings, hold-down lugs, and lifting lugs; laminate construction requirements such as structural tank, joints, and fittings and accessories; and other requirements such as physical properties, chemical resistance of resin, glass content, tensile strength, flexural properties and degree of cure. The dimensions and tolerances, as well as the workmanship, finish and appearance are also detailed.

1.1 This specification covers cylindrical tanks fabricated by contact molding for above-ground vertical installation, to contain aggressive chemicals at atmospheric pressure, and made of a commercial-grade polyester or vinyl ester, resin. Included are requirements for materials, properties, design, construction, dimensions, tolerances, workmanship, and appearance.

1.2 This specification does not cover the design of vessels intended for pressure above atmospheric or under vacuum conditions, except as classified herein, or vessels intended for use with liquids heated above their flash points.

1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are provided for information purposes only.

1.4 Special design consideration shall be given to tanks subject to environmental and/or mechanical forces such seismic, wind, ice, agitation, or fluid dynamic forces, to operational service temperatures greater than 180°F (82°C) and to tanks with unsupported bottoms.

1.5 The following safety hazards caveat pertains only to the test method portion, Section 11, of this specification: 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

Note 1: There is no known ISO equivalent to this standard.

1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.