Metric Translation
Metric Translation
(OP)
Anybody know why API 650 insists on translating 1 inch as 25mm. Giving grief on attaching equipment to large storage tanks
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS Come Join Us!Are you an
Engineering professional? Join Eng-Tips Forums!
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail. Posting GuidelinesJobs |
|
RE: Metric Translation
For example today we can buy soft drings in two-liter bottles in the USA. Oil is sold in quart containers. A quart is one fourth of a US gallon, not to be confused with a British gallon. Still I tell people to visualize a quart of oil to visualize a liter even though this lacks precision. The standard also lacks precision regarding temperature and pressure.
How many decimals would you prefer?
RE: Metric Translation
However, those tenths add up. Over the length of a foot, this is about a 5mm difference, about 3/16". It is up to us to convert precisely.
In API RP2a, have I not seen API use 50mm for 2 inches? In offshore construction, that is definitely close enough.
RE: Metric Translation
You ask "How many decimals would you prefer". That's an interesting question. With the Computers being used nowadays it's all to easy to get results with 3 to 4 decimal places (or more) and unfortunately there are younger engineers who think this accuracy is warranted. In the "olde" days calculations were not as accurate and several decimal places of accuracy were not provided (especially when slide rules were used) but plants were made and did not fall down (very often). It's now become the norm to provide displacement results to 3 decimals of a millimetre or three decimals of an inch which is ridiculous as confirmation of these displacements in the field is not possible without extensive surveying equipment. We all need to get back to reality as regards the required accuracy of computer results.
RE: Metric Translation
This problem was pointed out to API over 10 years ago (10th Edition) and so we are now on 11th Edition Add 2. So my question should more be why is API continuing to use 25mm to the inch.
RE: Metric Translation
This Standard has requirements given in two alternate systems of units. The Manufacturer shall comply with either:
1. all of the requirements given in this Standard in SI units, or
2. all of the requirements given in this Standard in US Customary units.
RE: Metric Translation
RE: Metric Translation
RE: Metric Translation
RE: Metric Translation
I would not have noticed if the dimension reflected 1-inch (25.4 mm). I would have noticed if the dimension reflected 25 mm (0.98425 inch).