This specification covers standard dimensional requirements for obtaining interchangeable spherical ground joints. This specification does not include physical, chemical, and design characteristics of material used. Dimensional requirements include socket member design, ball member design, size designation, dimensions, and interchangeability. Ground joints shall be tested for ball and socket dimensions and leakage. Leak rate shall be calculated based on change in differential pressure, evacuated volume and time of test.

1.1 This specification provides standard dimensional requirements for obtaining, within practical limits, interchangeability in spherical ground joints for ordinary laboratory and industrial applications. It covers dimensional interchangeability of the ground surfaces only and does not involve design characteristics of the item except where specified, nor does it involve physical or chemical characteristics of the material used.

Note 1--The dimensions pertaining to spherical ground joints were taken from the Commercial Standard CS 21-58 of the U.S. Department of Commerce.

Note 2--Although glass is the most commonly used material for ground joints, other materials may be used as specified. Spherical joints constructed from glass shall conform to Specifications E438 and E671.

1.2 The following precautionary caveat pertains only to the Test Method portion, Section 4, 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 and health practices and determine the applicability of regulatory limitations prior to use.