Internal coupler threads are protected by plastic plugs and external rebar threads are protected by plastic caps, both of which should be kept in place until the time of assembly. If missing, obtain the correct plugs/caps from the rebar splice manufacturer or supplier. If you see minor external thread damage, try using a thread file to correct the problem. For other thread damage, it may be necessary to use a thread die tool.

Do pay attention to below things.

Do not try to assemble damaged threads. You may cause premature binding.

Do not use this rebar coupler in conjunction with a rebar which is larger or smaller than the intended bar size.

Do not use anything other than unified national courses threads.

Do remember to store rebar couplers in a clean, dry place until they are ready to install.

If the rebar splice coupler is placed first, make sure the internal coupler thread is protected from the concrete before pouring concrete around or near the bar sleeve coupler. If present, make sure the coupler flange is properly secured to the form. Make sure the bar is properly supported and tied off. If the threaded rebar is placed first, make sure the rebar thread is protected from the concrete before pouring concrete around or near the thread. Do not place reinforcement bar or bar mechanical splice if the threads are damaged and cannot be repaired,

When joining the threaded rebar splice coupler, remove the protective caps and plugs and then line up both sides as straight as possible as shown in the pre-assembled condition below. 

Just before assembly, check both internal and external threads for cleanliness. Clean off any foreign matter. Do not use corrosive acids. Any thread damage must be corrected as noted above before installation.

After the initial thread location, rotate the free rebar clockwise making sure that the threaded ends remain aligned.

NOTE: If the threaded end of the rebar is bent, Do not align the rebars. Align the threads so that the threads screw together. Continue to rotate the free rebar by hand. If you feel the threads starting to prematurely bind, do not force them. Shake the free end of the rebar while turning. Allow the free end of the rebar to rotate in its own natural circle. ASSEMBLE UNTIL THREADS ARE FULLY ENGAGED.

If the threaded rebar end does not properly engage into the rebar splice coupler during assembly, stop immediately. Disassemble the connection to determine the problem. Possible causes of mis-assembly may be: mis-matched thread sizes; bars rubbing against each other; contaminated threads (i.e. concrete, dirt, etc.); or threads that have been damaged. Reassemble only after

the problem has been identified and corrected.

To ensure the threads are fully engaged, use a pipe wrench or chain wrench to snug and tighten the assembly. Long lengths of rebar, especially large diameter bars, are heavy. To overcome this bar weight, it may be necessary to use an extension bar. Make sure you are securely positioned and that you will not slip or fall during installation. Use only good quality wrenches that will not round-out.

Insert the threaded rebar end into the rebar splice coupler, and turn clockwise until the connection is snug. Once threads are fully engaged, turn the threaded bar one half additional turn into the coupler using a pipe or chain wrench as described above. If a setting bar was supplied with the coupler already attached, no additional installation is required on that bar. If both sides of the coupler require rebar to be installed into it, tighten the first side as described before tightening the second side as described.

Inspect the splice for proper thread engagement. For rebar splice threads, some variation in the number of exposed threads is natural due to thread tolerance build-up and thread run-out. In general, it is usual to see 0 to 1 threads after full assembly. Fully assembled threads can be double-checked by the application of a pipe wrench, which overcomes the weight of the bar as described above. IT IS NOT NECESSARY TO USE A TORQUE WRENCH OR APPLY A HIGH TORQUE VALUE.

When installing epoxy coated couplers and rebar, apply wrench to the rebar, not the rebar splice coupler. Once installed, touch-up damaged areas with epoxy repair kit. Seal off the rebar at the point of entry of the rebar into the coupler using epoxy repair material.