There is no specific standard for the length of rebar coupler, the JGJ107-2016 "Technical Regulations for Mechanical Connection of Steel Bars" also does not clearly stipulate the length and outer diameter of rebar coupler. The JG/T163--2013 (Technical Regulations for Mechanical Connection of Reinforced Bars) specified the yield and outer diameter of rebar coupler, and the small size table of standard cylindrical straight threaded sleeves made of No. 45 steel material is supplemented, the length of the steel bar sleeve produced by it is: 16:40mm, 18:45mm, 20:50mm-55mm, 25:60mm, 28:70mm, 32:75mm.

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