ASME Section VIII edition 2004, is endorsing two separate Units of Mea

[LSThill]

TEAM MEMBER'S:

As you are aware, ASME Section VIII edition 2004, is endorsing two separate Units of Measurements (UM), and mandatory requires to use them as stand alone through out the design, procurement and fabrication phases. As a result it is clearly stated that using transformation coefficients in the calculations is banned.

code case had been issued last Friday postponing the units requirement. Would you find out about this and let me know the code case number and, if you can, send a copy of the code case?

 

[JoeTank]

We are inching closer to SI units every day it seems.

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com

 

[waskillywabbit]

Steve,

Don't you mean we are "millimetering" closer every day!

We might use SI units in 1 out of 100 units fabricated and then both are usually on the drawing.

Brian

 

[jte]

Leonard-

I don't know about the code case - it's not up on the ASME site yet

http://cstools.asme.org/CodeCases.cfm

If you thought allowing dual systems (completely metric or completely U.S. customary) was bad, read the forward to B16.5 2004: The 2003 Edition includes metric units as the primary reference units while maintaining U.S. customary units in either parenthetical or separate forms. The goal is to delete the U.S. customary units when the standard is next issued.

jt

 

[LSThill]

jte (Mechanical)

jte

For the "PRESSURE VESSEL SOFTWARE" user this and EPC contractor, fabricator is trying to understand the below:

As you are aware, ASME Section VIII edition 2004, is endorsing two separate Units of Measurements (UM), and mandatory requires to use them as stand alone through out the design, procurement and fabrication phases. As a result it is clearly stated that using transformation coefficients in the calculations is banned.

"PRESSURE VESSEL SOFTWARE" shall clearly state if their software is compliant and validated with both metric and U.S. customary UM of the ASME sect. VIII 2004 edition.

Jte: thank you for the ASME code case Link.

 

[weldtek]

When the change from Imperial to Metric took place in Canada, back in the 70's, most of us found the transition to be the worst part. During that period we had two systems, fab drawings showed measurements in both systems, we had tape measures marked in both systems, etc. That was difficult, but once we were immersed in metric, and adjusted, most people preferred it.

 

[reichertc]

jte,

The B16.5 forward may sound very scary, but I read a paper issued by the B16 committee on the "metrification" of the standard, and they seem to have done a very good job of it and given it a lot of thought. Rather than simply multiplying by 25.4 and giving the answeer to an undefined number of significant digits, they evaluated each conversion to determine the necessary number of significant digits that need to be carried, and wheter to round to the nearest 5mm, 1mm, 0.1mm, etc. They also didn't base the conversion upon the previously published decimal inches (which are rounded values), but went back to the underlying fractional inches to perform the conversion. They ensured that a "metric" flange would be able to bolt up to an "imperial" flange. Finally, they made sure that by converting to metric, equipment to manufacture the flanges should not have to require significant modifications.

Kudos to the B16 team that did this. Best job of metrification that I've seen done.

Original article at

http://cstools.asme.org/csconnect/pdf/CommitteeFiles/12173.pdf

Good reading, check it out.

 

[LSThill]

CASE
Use of Metric Units
Boiler and Pressure Vessel Code Sections I, III, IV, V, VIII, Divisions 1, 2 & 3, X, IX and XII

Inquiry: Under what conditions may a Manufacturer use a mixed system of units (e.g. a combination of U.S. Customary units, SI units and / or local customary units) to demonstrate compliance with all of the requirements of Sections I, III, IV, V, VIII Divisions 1, 2 & 3, X, IX and XII of the Boiler and Pressure Vessel Code?

Reply: It is the opinion of the Committee that a Manufacturer may use a mixed system of units (e.g. a combination of U.S. Customary units, SI units and / or local customary units) to demonstrate compliance with all of the requirements of Sections I, III, IV, V, VIII Divisions 1, 2 & 3, X, IX and XII of the Boiler and Pressure Vessel Code under the following conditions:

 

[tmdixon]

I'm waiting....what are the conditions?

 

[unclesyd]

That's in the next edition.

 

[LSThill]

CASE:
Use of Metric Units
Boiler and Pressure Vessel Code Sections I, III, IV, V, VIII, Divisions 1, 2 & 3, X, IX and XII

Inquiry: Under what conditions may a Manufacturer use a mixed system of units (e.g. a combination of U.S. Customary units, SI units and / or local customary units) to demonstrate compliance with all of the requirements of Sections I, III, IV, V, VIII Divisions 1, 2 & 3, X, IX and XII of the Boiler and Pressure Vessel Code?

Reply: It is the opinion of the Committee that a Manufacturer may use a mixed system of units (e.g. a combination of U.S. Customary units, SI units and / or local customary units) to demonstrate compliance with all of the requirements of Sections I, III, IV, V, VIII Divisions 1, 2 & 3, X, IX and XII of the Boiler and Pressure Vessel Code under the following conditions:

(a) For any single equation, all variables must be expressed in a single system of units.

(b) When separate equations are provided for US Customary and SI units, those equations must be executed using variables with the specific associated units system. Data expressed in other units shall be converted to U.S. Customary or SI units for use in these equations. The result obtained from execution of these equations may be converted to other units.

(c) Production measurement and test equipment, drawings, welding procedure specifications, welding procedure and performance qualifications, and other fabrication documents may be in U.S. Customary, SI or local customary units in accordance with the fabricator’s practice. When values shown in calculations and analysis, fabrication documents or measurement and test equipment are in different units, one or the other value shall be converted in accordance with paragraphs (g) and (h) to provide consistent units when necessary for verification of Code compliance.

(d) Material that has been manufactured and certified to either the U.S. Customary or SI material specification (e.g. SA-516 or SA-516M) may be used regardless of the unit system used in design.

(e) Standard fittings (e.g., flanges, elbows, etc.) that have been certified to either US Customary units or SI units may be used regardless of the units system used in design.

(f) Soft conversion of units, using the precision specified in paragraphs (g) and (h) shall be performed to assure that dimensional consistency is maintained. Soft conversion factors between US Customary and SI units may be found in the Nonmandatory Appendix, Guidance for the Use of US Customary and SI Units in the ASME Boiler and Pressure Vessel Code. Whenever local customary units are used the Manufacturer shall provide the source of the conversion factors which shall be subject to verification and acceptance by the Authorized Inspector or Certified Individual.

(g) Conversion factors shall be accurate to at least four significant figures.

(h) The results of conversions of units shall be to a minimum of three significant figures.

(i) All entries on a Manufacturer’s Data Report shall be in units consistent with the fabrication drawings for the component using U. S. Customary, SI or local customary units. It is acceptable to show alternate units parenthetically.

(j) U.S. Customary, SI or local customary units may be used for the Code required nameplate marking consistent with the units used on the Manufacturer’s Data Report. It is acceptable to show alternate units parenthetically.

(k) This Case shall be shown on the Manufacturer’s Data Report.

If you have any questions or comments, please post them!

 

[tmdixon]

I am relieved to read points d and e, it was my original understanding that if our shop purchased plate/ fittings etc in US units (which is what is readily avaiable), then we could not manufacture/design in SI units (which is what our customer's require). Is it your opinion, Isthill that this is no longer a requirement under the current code?

 

[deanc]

Code Case 2523. It has not yet passed!!!! Be careful. Talk to your AIA.

Read the "Forward" of each section. More to come.

 

[torsani]

In other countries, as Brazil, we have been using both metric and customary units for a long time. The standard system is SI but some parts, as bolts and fittings, are used in customary units. In Brazil metric bolts, for example, are according DIN standard and it isn't according metric ANSI.

For us, who are living in a metric world, the ASME conversions like confused!

For the ASME, could we use customary bolts and fittings in a SI vessel?

Best regards