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I am using a LSAW 16mm(OD) pipe, and I need to have a smooth and uniform surface inside it so a piston can reciprocate easily inside it. What is the best and fastest way to remove the inside weld line? It is going to be part of a production line, therefore, the speed of this process is very important.

Amir
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  • Have it machined. But what length? like hydraulic cylinders the tools required can be long. – Solar Mike Aug 20 '20 at 10:30
  • They are about 12cm tall. I'm planning to produce at least 1000 of these per day; therefore, I'm not sure whether machining is the best way or not. – Amir Aug 20 '20 at 15:57
  • What is LSAW.? Certainly not longitudinal submerged arc weld on very small pipe . – blacksmith37 Aug 20 '20 at 18:13
  • I can also buy ERW pipes, but they are a little less available for me at the moment. But I have to come up with most economic solution possible. I would appriciate your suggestion. – Amir Aug 20 '20 at 18:23
  • That is a small size even for ERW. I suspect pipe that is sold as ERW is welded at about 50 mm and then cold drawn for small sizes. One US maker welds at 150 mm and cold draws to produce all smaller sizes. – blacksmith37 Aug 20 '20 at 21:39
  • Need more details about the piston to determine how you need to prepare the cylinder. Mate a simple drill-driven bore polisher or flex hone would suffice. Otherwise machining, boring, honing etc may be in order. – GisMofx Aug 21 '20 at 12:06
  • It's for gas struts used in kitchen cabinets. They have steel rod and plastic piston head, sealed with NBR o'ring and rod Seal, and filled with Nitrogen gas under 6-7bar pressure. – Amir Aug 21 '20 at 17:02

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In order to have an internal surface of sufficient surface finish for a piston to seal properly, the cylinder must be internally machined. Properly, it should be bored and honed. To speed up the process, it may be reamed and polished or perhaps burnished, depending on the sealing/pressure required, that may not be sufficient enough.

Corey
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  • I was considering to cold draw them to remove the weld line, but I realized the inside surface wouldn't be as accurate and smooth as needed. Maybe if I cold draw ERW pipes instead of LSAW pipes, I get the desired result. – Amir Aug 20 '20 at 16:02