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摘要

To tighten a high strength bolt, should I place the impact wrench on the head of the bolt, or on the nut?rnField conditions may require a high strength bolt to be tightened by placing the impact wrench on the bolt head instead of on the nut. The AREMA Manual forRailwaylngineeringptwies guidelines for this situation. AREMA Chapter 15, Steel Structures, Table 15-3-3, Nut Rotation from Snug-Tight Condition, identifies the required rotation needed: for various sizes and conditions of high strength bolt installations. ThiStabfe includes a reference "Note" that states: "Nut rotation is relative to bolt regardless of theelement (nut or bolt) ieiftg turned." When it has determined if the turned element will fee the nut or the bdlt, keep in mind that REMA also States that "high strength bolts shall have a hardenedwasher under the turned element." If you use A490 bolts ifth structural steel having a yield point less ttian 40M, you will need to have hardenfeirashers on both the turned arid the non-turned element.