Cut or Drill? - CR4 Discussion Thread

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unns_boy Member Join Date: Sep 2011 Posts: 5	Cut or Drill? 08/13/2012 10:40 AM
	Hi, I am trying to fabricate a 304 stainless steel fire tube heat exchanger as sketched. My concern is, can I cut all the holes on both tube walls with plasma cutter or should I drill them? Does plasma cutting have any bad effect on the 304? Since the heat exchanger will be under thermal stress, will plasma cutting weaken the welding area or cause metal fatigue? All suggestions, comments and advice are most welcome. Thank you. Yip
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PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#1 Re: Cut or drill? 08/13/2012 10:45 AM
	Discuss the matter with the Engineer/Surveyor from the company that is to provide burst indemnity insurance cover on the equipment, as it looks like a fire tube boiler, and there is a lot more to making a boiler than merely drilling a few holes in a tubeplate. Is that sketch all there is, or is there a detailed mechanical drawing? Process fluid, its temperature and pressure? Where is the stress analysis calculation, showing the location, diameter and number of the stays? What is the intended rating of this equipment? Installation location? Etc. __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
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phoenix911 Guru Join Date: Aug 2007 Posts: 23647 Good Answers: 420	#2 Re: Cut or drill? 08/13/2012 10:50 AM
	Does plasma cutting have any bad effect on the 304? warpage, looser tolerance Drilling would be more accurate. with tighter tolerances. back to the principal. this is dangerous. What do you plan on accomplishing here? I do not see any safety devices such as pressure relief, What is your goal of temperature and pressure requirements, being a fire tube, what is your fire box contructed out of? what are you tubes made out of? How are you going to deal with thermal expansion of the tubes? What type and spec. of tube are you going to use? What Material of tube or you going to use? some dimensions would also help? to start with. __________________ “ When people get what they want, they are often surprised when they get what they deserve " - James Wood
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mike k Guru Join Date: Apr 2008 Location: Bristol, Tennessee Posts: 1177 Good Answers: 58	#3 Re: Cut or Drill? 08/13/2012 5:18 PM
	Yup, you need to learn about boilers. Google boiler explosions, images. One this size will take out the average house. You need a degree and a license to build and fire up a boiler. Otherwise, insurance will not pay damages, including death benefits. No joke. On topic, to make the cleanest holes, see if an electrician's chassis punch/hole punch will make a hole the size of your tube, or get tubes to fit the holes those punches will make, they get quite large. Perfect circles, clean cut, easy to do once you get the proper equipment. __________________ mike k
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mike k Guru Join Date: Apr 2008 Location: Bristol, Tennessee Posts: 1177 Good Answers: 58	#7 In reply to #3 Re: Cut or Drill? 08/17/2012 1:28 PM
	As a follow-up to this project, the hole punches can be rented, with a nice hydraulic cylinder and pump to do the hard work. __________________ mike k
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unns_boy Member Join Date: Sep 2011 Posts: 5	#4 Re: Cut or Drill? 08/14/2012 6:52 AM
	The heat exchanger is actually located in a square open top tank for heating water to 60 deg C. The volume of water to be heated will be around 1000 Liter. Level sensor and temperature sensor will also be installed. All the parts will be of 304 s/s.
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PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#5 In reply to #4 Re: Cut or Drill? 08/14/2012 10:20 AM
	The original sketch, and the post it is in, do not state this. __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
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ducon Guru Join Date: Dec 2006 Location: Hop around Toronto, New York & Karachi Posts: 1876 Good Answers: 19	#6 In reply to #4 Re: Cut or Drill? 08/17/2012 1:00 AM
	It is still a Boiler > Hot water Boiler. __________________ I not only use all the brains that I have, but all that I can borrow. Woodrow Wilson
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Users who posted comments:

ducon (1); mike k (2); phoenix911 (1); PWSlack (2); unns_boy (1)

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