Stainless steel has a very thin oxide film on all surfaces which develops naturally and provides corrosion resistance. Thread galling occurs when the oxide layer gets rubbed off and deposited on a mating surface leading to high-spots. These in turn lead to more material being transferred and ultimately, if not checked, the two surfaces can bind together permanently.
Prevention
- All threads are clean and free running prior to despatch and in cases where we have mating stainless steel threads a thin Teflon based lubricant is applied during assembly.
- Keep threads clean - do not allow threads to rest on the ground or on dirty surfaces. Do not remove items from their original packaging until you are ready to install them. If the packaging was damaged during transit inspect all threads for signs of damage and re-pack until you are ready to use them. If installation is being done on a windy day be sure to check for dirt, sand and fine grit particles before adjusting any threads.
- Avoid damage to threads - dints and lumps on threads can be easily caused by mishandling. Large threads can be damaged by their self-weight if allowed to drop even short distances. Large threads are packed with a protective mesh which should not be removed until the very last moment. Ideally work above a rubber mat. If you spot damage please contact us before attempting any rectification or assembly.
- Do not use stainless steel on stainless steel for tensioning - the increase in friction increases the likelihood of galling. Tension members should be jacked to take the load and then adjusted.
- Do not apply grease to threads - dirt, sand and grit are more likely to stick to grease. If required then a Teflon based lubricant or alternatively a thin lubricant such as WD-40 should be used.
- Threads should always be free-running - if a thread feels rough or tight stop immediately and seek assistance.
Rectification
Impurities trapped in the threads and damage caused by careless handling can cause thread galling. When this happens it may become impossible to free or adjust the mating threads. The steps below can, in our experience, occasionally release seized threads that are not too far damaged. We accept no liability for damage or loss caused by following these steps and they are not guaranteed to work.
- If a thread becomes rough or tight stop adjustment immediately. Spray WD-40 or equivalent between the mating thread and leave for a couple of minutes to allow the oil to penetrate. A sharp but light tap can sometimes free the problem temporarily. Turn one full rotation out and then 1/2 a rotation in. Continue to do this until the thread is released.
- Once the thread is released clean thoroughly and inspect both internal and external threads for damage, dirt and material pick-up.
- Apply thread lubricant and try to rewind the thread. If the problem persists then contact us immediately for further guidance.
- NEVER TRY TO FORCE A THREAD ON - this will lead to permanent galling.
- NEVER TRY TO RELEASE WITH HEAT - incorrect heating can alter the physical properties of the material.