【国外标准】 Standard Specification for Non-Asbestos Fiber-Cement Conduit

This specification covers non-asbestos fiber-cement conduit for use in electric-power systems and communication systems. The service is for both underground and exposed conditions. The classes of conduit shall be as follows: Class B which is intended for use encased in concrete after installation and Class B which is intended for use without concrete encasement, or for exposed services. The types of conduit shall be known as Type I and Type II corresponding to the chemical requirements specified. Type I is to be used where nonaggressive water and soil of moderate surface content are expected to come in contact with the conduit. Type II is to be used where moderately aggressive water or water and soil of high sulfate content, or both, are expected to come in contact with the conduit. Fiber-cement conduit shall be composed of an intimate mixture of an inorganic hydraulic binder or a calcium silicate binder formed by the chemical reaction of a siliceous material and a calcareous material reinforced by organic fibers, inorganic non-asbestos fibers, or both. Process aids, fillers and pigments which are compatible with fiber-reinforced cement are not prohibited from being added. All material shall be of laminar construction formed under pressure to a homogeneous structure and cured to meet the physical and chemical requirements. Mechanical properties like flexural strength and crushing strength of the conduit shall be determined.1.1 This specification covers non-asbestos fiber-cement conduit for use in electric-power systems and communication systems. The service is for both underground and exposed conditions.1.2 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the specification.1.3 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.1.4 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.