Re: Testing fuel tanks
Hi Thanks for the reference. Jeffrey Williams wrote: [Big snip] And please, if you feel very confident in your own analytical ability, review a copy of the ASME Code and get a copy of Formulas for Stress and Strain by R.J. Roark before you inadvertantly build yourself a bomb. I have just ordered a copy of Roark (the new 7th edition). Ta. Best wishes, Susan.
Re: Testing fuel tanks
Hello Jeffrey, When I was in the design office using the ASME Section 8 Code, typical numbers for common pressure vessel steel were: Ultimate Strength 55,000 psi Factor of Safety 4 Therefore Design Stress 13,750 psi. The Yield Strength (about 30,000psi) was never used for design. Factor of Safety of 3 was only used for atomic reactors and other very carefully controlled constructions. Actually the ASME Code is not intended for designing things like our fuel tanks. Flat sides, silver brazing, brass, bronze, copper, threads, are hardly touched on. It was recognized that the yield strength was likely exceeded locally due to stress-concentration during the hydro pressire test. But thereafter, it would not be exceeded in service. In a refinery, the most highly-stressed vessels are the large storage tanks (not covered under ASME) and other than weld radiography, only testable by filling with water. Cheers, Peter Trounce. - Original Message - From: Jeffrey Williams [EMAIL PROTECTED] To: Multiple recipients of sslivesteam [EMAIL PROTECTED] Sent: Wednesday, January 21, 2004 10:52 PM Subject: Testing fuel tanks I'm concerned that there is an impression out there that there exists some standard or traditional test pressure that is correct for all fuel tanks or other pressure vessels (including boilers). Various numbers like 350 psi or 160 psi have been proposed. My recently purchased Accucraft 3-cylinder Shay came with a certificate which claims that the butane fuel tank was tested to 160 psi. There is an old adage in mechanical engineering that says you can't test in safety - or maybe it's an adage of old mechanical engineers - I can't remember! The safety of a system comes from its design, including dimensions, material selection, joining techniques, reinforcing details, penetrations and a host of other factors, not from one proof test. Testing of a system can be done to verify analysis done in support of the design, but a vessel that is tested, intensionally or accidentally, to stress levels above the yield strength of even one of its components is not a safe vessel, because the test has already caused the material, joints, reinforcements and/or penetrations to plastically deform and become unsafe. The only possible way that pressure testing guarantees safety is if a manufacturer is willing to subject a very large number of identical vessels to a test-to-failure to gather statistics that also support the original design limits of a vessel. Yes, it is possible that a single pressure test, if improperly defined and carried out can in fact decrease safety, rather than ensure it. The ASME Boiler and Pressure Vessel Code has been around for almost a century in order to bring science (and safety) to pressure vessel design, testing and operation. The Code not only defines acceptable methods of design and construction, but also material selection, joining, repairing, inspection and testing. University engineering libraries will have a copy of the Code if you are interested or you can buy it from ASME for a very large sum of money. Pressure vessels are designed with a safety factor in mind (often a minimum factor of 3) to the yield strength of the materials used in construction of the vessel. In other words, at maximum operating pressure and temperature, every part and component of the pressure vessel will experience stresses of no more than 1/3 of the yield strength of the material at that temperature. Other safety factors may be chosen for different applications, depending on the consequence of failure and the precision with which the designer knows the as-built dimensions and material properties. There are lots of subtleties like fracture toughness, stress concentrations, anticipated future loads, damage or corrosion and low-temperature transition temperatures, etc. that can also bite you if you're not careful. It's my suggestion that people who do not have training and experience in strength of materials calculations be incredibly careful when embarking on the design and construction of any pressure vessel whether it's a fuel tank, boiler or other vessel. Make friends with a trained mechanical (or sometimes chemical) engineer so that he or she can review your design and your fabrication and testing plans. The live steam fraternity has plenty of us mechanical engineers who are attracted to the hobby because of its application of very pure and basic engineering principles, so you should be able to find someone of appropriate background who would be happy to review your pressure vessel design. And please, if you feel very confident in your own analytical ability, review a copy of the ASME Code and get a copy of Formulas for Stress and Strain by R.J. Roark before you inadvertantly build yourself a bomb.
Re[2]: Butane/Propane Fuel tank Pressure?
I have been following this subject with some interest. I do not want anyone for one moment to suspect that I have no respect for pressure and what it can do. (engineers out there may have read the Cockenzie report years ago). I am holding in my hands a gas canister it is about 8 inches high and about 2.5 inches diameter. it is a butane propane mixture (30%) these cans get left in direct sun on construction sites all over the world The temperatures can be at times to hot to hold almost. These cans are on sale at all hardware suppliers the material is under 1mm thick. I am for safety very much, but I sometimes get the feeling that in our belt and braces society of today there may be a tendance to exaggerate. Has anyone done the calculations on these cans?. Just an example a Champagne bottle holds up to 150 psi with a cork and a bit of wire. A bomb? These are just thoughts and they may cause someone to come with a not so dramatic solution. I am not suggesting making a gas tank of 1mm tin plate. Bert. - Bert Edmunda [EMAIL PROTECTED]
Re: Testing fuel tanks
Hello Jeffrey, Seems to me you might want to purchace a fuel tank from Cheddar or Roundhouse. Why reinvent thewheel, so to speak? From: "Peter Trounce" <[EMAIL PROTECTED]>Reply-To: [EMAIL PROTECTED] To: Multiple recipients of sslivesteam <[EMAIL PROTECTED]>Subject: Re: Testing fuel tanks Date: Thu, 22 Jan 2004 10:39:56 -0500 Hello Jeffrey, When I was in the design office using the ASME Section 8 Code, typical numbers for common pressure vessel steel were: Ultimate Strength 55,000 psi Factor of Safety 4 Therefore Design Stress 13,750 psi. The Yield Strength (about 30,000psi) was never used for design. Factor of Safety of 3 was only used for atomic reactors and other very carefully controlled constructions. Actually the ASME Code is not intended for designing things like our fuel tanks. Flat sides, silver brazing, brass, bronze, copper, threads, are hardly touched on. It was recognized that the yield strength was likely exceeded locally due to stress-concentration during the hydro pressire test. But thereafter, it would not be exceeded in service. In a refinery, the most highly-stressed vessels are the large storage tanks (not covered under ASME) and other than weld radiography, only testable by filling with water. Cheers, Peter Trounce. - Original Message - From: "Jeffrey Williams" <[EMAIL PROTECTED]>To: "Multiple recipients of sslivesteam" <[EMAIL PROTECTED]>Sent: Wednesday, January 21, 2004 10:52 PM Subject: Testing fuel tanks I'm concerned that there is an impression out there that there exists some standard or traditional test pressure that is correct for all fuel tanks or other pressure vessels (including boilers). Various numbers like 350 psi or 160 psi have been proposed. My recently purchased Accucraft 3-cylinder Shay came with a certificate which claims that the butane fuel tank was tested to 160 psi. There is an old adage in mechanical engineering that says "you can't test in safety" - or maybe it's an adage of old mechanical engineers - I can't remember! The safety of a system comes from its design, including dimensions, material selection, joining techniques, reinforcing details, penetrations and a host of other factors, not from one "proof" test. Testing of a system can be done to verify analysis done in support of the design, but a vessel that is tested, intensionally or accidentally, to stress levels above the yield strength of even one of its components is not a safe vessel, because the test has already caused the material, joints, reinforcements and/or penetrations to plastically deform and become unsafe. The only possible way that pressure testing "guarantees" safety is if a manufacturer is willing to subject a very large number of identical vessels to a test-to-failure to gather statistics that also support the original design limits of a vessel. Yes, it is possible that a single pressure test, if improperly defined and carried out can in fact decrease safety, rather than ensure it. The ASME Boiler and Pressure Vessel Code has been around for almost a century in order to bring science (and safety) to pressure vessel design, testing and operation. The Code not only defines acceptable methods of design and construction, but also material selection, joining, repairing, inspection and testing. University engineering libraries will have a copy of the Code if you are interested or you can buy it from ASME for a very large sum of money. Pressure vessels are designed with a "safety factor" in mind (often a minimum factor of 3) to the yield strength of the materials used in construction of the vessel. In other words, at maximum operating pressure and temperature, every part and component of the pressure vessel will experience stresses of no more than 1/3 of the yield strength of the material at that temperature. Other safety factors may be chosen for different applications, depending on the consequence of failure and the precision with which the designer knows the as-built dimensions and material properties. There are lots of subtleties like fracture toughness, stress concentrations, anticipated future loads, damage or corrosion and low-temperature transition temperatures, etc. that can also bite you if you're not careful. It's my suggestion that people who do not have training and experience in "strength of materials" calculations be incredibly careful when embarking on the design and construction of any pressure vessel whether it's a fuel tank, boiler or other vessel. Make friends with a trained mechanical (or sometimes chemical) engineer so that he or she can review your design and your fabrication and testing plans. The live steam fraternity has plenty of us mechanical engineers who are attracted to the hobby because of its application of very pure and basic engineering principles, so you should be able to find someone of appropriate background who would be happy
RE: Testing fuel tanks
The last time I priced them from cheddar they were over 100 USD might be more now with the value of the dollar. I am getting the feeling these days when I have aquired a sizable inventory of fabrication/building skills and knowledge that I can build many items that are otherwise unaffordable to the hobby budget or make the available budget go further. If the items are reasonably cheap compared to the time it takes to fabricate then I will usually buy without much thought. For less than 30 USD in parts that are needed to be purchased, I could make any size tank. I made a large boiler for my model steamboat in a size that would have cost 7-800 USD if you could find one. I was able to make it for about 200 dollars in parts and materials. If you have the skills to build then sometimes it makes the hobby fairly affordable, and besides I really like making this stuff which is actually the most important part. Steve -Original Message- From: Daniel McGrath [SMTP:[EMAIL PROTECTED] Sent: Thursday, January 22, 2004 3:22 PM To: Multiple recipients of sslivesteam Subject: Re: Testing fuel tanks Hello Jeffrey, Seems to me you might want to purchace a fuel tank from Cheddar or Roundhouse. Why reinvent the wheel, so to speak? From: Peter Trounce Reply-To: [EMAIL PROTECTED] To: Multiple recipients of sslivesteam Subject: Re: Testing fuel tanks Date: Thu, 22 Jan 2004 10:39:56 -0500 Hello Jeffrey, When I was in the design office using the ASME Section 8 Code, typical numbers for common pressure vessel steel were: Ultimate Strength 55,000 psi Factor of Safety 4 Therefore Design Stress 13,750 psi. The Yield Strength (about 30,000psi) was never used for design. Factor of Safety of 3 was only used for atomic reactors and other very carefully controlled constructions. Actually the ASME Code is not intended for designing things like our fuel tanks. Flat sides, silver brazing, brass, bronze, copper, threads, are hardly touched on. It was recognized that the yield strength was likely exceeded locally due to stress-concentration during the hydro pressire test. But thereafter, it would not be exceeded in service. In a refinery, the most highly-stressed vessels are the large storage tanks (not covered under ASME) and other than weld radiography, only testable by filling with water. Cheers, Peter Trounce. - Original Message - From: Jeffrey Williams To: Multiple recipients of sslivesteam Sent: Wednesday, January 21, 2004 10:52 PM Subject: Testing fuel tanks I'm concerned that there is an impression out there that there exists some standard or traditional test pressure that is correct for all fuel tanks or other pressure vessels (including boilers). Various numbers like 350 psi or 160 psi have been proposed. My recently purchased Accucraft 3-cylinder Shay came with a certificate which claims that the butane fuel tank was tested to 160 psi. There is an old adage in mechanical engineering that says you can't test in safety - or maybe it's an adage of old mechanical engineers - I can't remember! The safety of a system comes from its design, including dimensions, material selection, joining techniques, reinforcing details, penetrations and a host of other factors, not from one proof test. Testing of a system can be done to verify analysis done in support of the design, but a vessel that is tested, intensionally or accidentally, to stress levels above the yield strength of even one of its components is not a safe vessel, because the test has already caused the material, joints, reinforcements and/or penetrations to plastically deform and become unsafe. The only possible way that pressure testing guarantees safety is if a manufacturer is willing to subject a very large number of identical vessels to a test-to-failure to gather statistics that also support the original design limits of a vessel. Yes, it is possible that a single pressure test, if improperly defined and carried out can in fact decrease safety, rather than ensure it. The ASME Boiler and Pressure Vessel Code has been around for almost a century in order to bring science (and safety) to pressure vessel design, testing and operation. The Code not only defines acceptable methods of design and construction, but also material selection, joining, repairing, inspection and testing. University engineering libraries will have a copy of the Code if you are interested or you can buy it from ASME for a very large sum of money. Pressure vessels are designed with a safety factor in mind (often a minimum factor of 3) to the yield strength of the materials used in construction of the vessel. In other words, at maximum operating pressure and temperature, every part and component of the pressure vessel will experience stresses of no more than 1/3 of the yield strength of the material at that temperature.
RE: Testing fuel tanks
Steve, I agree to a great part. The fuel tanks can be purchased from Sulpher Springs, they would cost for the largest ones about $100.00. I can't believe it would take that much engineering to produce on of these tanks as sugguested by some of the replys, safety of course is a prime factor. I don't want to guess, but it seems that the same method and dimensions used to produce a boiler would be enough for a fuel tank. By demensions I refer to thickness of the copper, brass wall used for the vessel Good Luck, I'm sure you will suceed. Dan McGrath From: "Ciambrone, Steve @ OS" <[EMAIL PROTECTED]>Reply-To: [EMAIL PROTECTED] To: Multiple recipients of sslivesteam <[EMAIL PROTECTED]>Subject: RE: Testing fuel tanks Date: Thu, 22 Jan 2004 15:39:57 -0800 The last time I priced them from cheddar they were over 100 USD might be more now with the value of the dollar. I am getting the feeling these days when I have aquired a sizable inventory of fabrication/building skills and knowledge that I can build many items that are otherwise unaffordable to the hobby budget or make the available budget go further. If the items are reasonably cheap compared to the time it takes to fabricate then I will usually buy without much thought. For less than 30 USD in parts that are needed to be purchased, I could make any size tank. I made a large boiler for my model steamboat in a size that would have cost 7-800 USD if you could find one. I was able to make it for about 200 dollars in parts and materials. If you have the skills to build then sometimes it makes the hobby fairly affordable, and besides I really like making this stuff which is actually the most important part. Steve-Original Message- From: Daniel McGrath [SMTP:[EMAIL PROTECTED] Sent: Thursday, January 22, 2004 3:22 PM To: Multiple recipients of sslivesteam Subject: Re: Testing fuel tanks Hello Jeffrey, Seems to me you might want to purchace a fuel tank from Cheddar or Roundhouse. Why reinvent the wheel, so to speak? From: "Peter Trounce" Reply-To: [EMAIL PROTECTED] To: Multiple recipients of sslivesteam Subject: Re: Testing fuel tanks Date: Thu, 22 Jan 2004 10:39:56 -0500 Hello Jeffrey, When I was in the design office using the ASME Section 8 Code, typical numbers for common pressure vessel steel were: Ultimate Strength 55,000 psi Factor of Safety 4 Therefore Design Stress 13,750 psi. The Yield Strength (about 30,000psi) was never used for design. Factor of Safety of 3 was only used for atomic reactors and other very carefully controlled constructions. Actually the ASME Code is not intended for designing things like our fuel tanks. Flat sides, silver brazing, brass, bronze, copper, threads, are hardly touched on. It was recognized that the yield strength was likely exceeded locally due to stress-concentration during the hydro pressire test. But thereafter, it would not be exceeded in service. In a refinery, the most highly-stressed vessels are the large storage tanks (not covered under ASME) and other than weld radiography, only testable by filling with water. Cheers, Peter Trounce. - Original Message - From: "Jeffrey Williams" To: "Multiple recipients of sslivesteam" Sent: Wednesday, January 21, 2004 10:52 PM Subject: Testing fuel tanks I'm concerned that there is an impression out there that there exists some standard or traditional test pressure that is correct for all fuel tanks or other pressure vessels (including boilers). Various numbers like 350 psi or 160 psi have been proposed. My recently purchased Accucraft 3-cylinder Shay came with a certificate which claims that the butane fuel tank was tested to 160 psi. There is an old adage in mechanical engineering that says "you can't test in safety" - or maybe it's an adage of old mechanical engineers - I can't remember! The safety of a system comes from its design, including dimensions, material selection, joining techniques, reinforcing details, penetrations and a host of other factors, not from one "proof" test. Testing of a system can be done to verify analysis done in support of the design, but a vessel that is tested, intensionally or accidentally, to stress levels above the yield strength of even one of its components is not a safe vessel, because the test has already caused the material, joints, reinforcements and/or penetrations to plastically deform and become unsafe. The only possible way that pressure testing "guarantees" safety is if a manufacturer is willing to subject a very large number of identical vessels to a test-to-failure to gather statistics that also support the original design limits of a vessel. Yes, it is possible that a single pressure test, if improperly defined and carried out can in fact decrease safety, rather than ensure it. The ASME Boiler and Pressure Vessel Code has been around for
Re: Announcing arrival of a new (3 cylinder) baby!
Wow, the 3-cyl model must be a real MULE How much bigger is it than the 2-cyl ??? Size and weight?? Am having a ball with my little 2-cyl model, but that 3-banger sounds like it could pull stumps out of the ground :-) Bob Magill - Original Message - From: Steamedup [EMAIL PROTECTED] To: Multiple recipients of sslivesteam [EMAIL PROTECTED] Sent: Tuesday, January 20, 2004 11:45 AM Subject: Re: Announcing arrival of a new (3 cylinder) baby! Jeff: I was just at Diamondhead and although I have not seen the results, I did hear that the Accucraft 3cyl Shay did out pull the Accucraft K-27. The results will probably be posted on SitG like they were last year. Congrats on the new Loco. I only saw three of the new Shays down at Diamondhead. John Fuller Troy, MI UPS delivered my Accucraft 3 cylinder Shay this afternoon. Serial #2 if I read the paperwork correctly. It's a thing of beauty and complexity! It comes with some assembly required and no assembly instructions so it will likely be a few days before I get to fire it up. Some new-to-Accucraft features that weren't advertized that I already like: 1. Hinged cab roof instead of the fiddly slide-on roof per other Accucraft live steamers 2. Water pump inside water/fuel tank. Tank volume probably around 16 oz. Dwight Ennis took delivery of his unit before New Years and posted some photos and a video on www.mylargescale.com/. Go to forums and then live steam Got to get moving on some rolling stock now - it will look silly pulling DRGW cars! And the big question - will it out-pull my K-27? John Fuller Live Steam, the only way to travel! http://www.smallscalelivesteamers.info
