Hammer Union Standard?

Here is a good brief that not only explains hammer unions, but the limitations and hazards - and how much trouble you might be in - there only seem to material standards.

The unions themselves seem to be unfortunately unregulated.

Presently (08/10) no industry standard exists for Wing Hammer Unions. A previous post offers a link to a Dowell/Schlumberger document warning about problems that exist as a result of no standard.

The warning document advises the use of only unions made by FMC. Although FMC originated the now popular Figure # unions, several competent manufacturers have reverse engineered the FMC design and produced high quality interchangeable unions.

Keep in mind that reverse engineering differs from copying, and many other manufacturers have made dimensionally similar unions that may not have the reliability of the original design.

These products have many problems associated with their use, and unless you intend to devote considerable time to the study and definition of these problems, you may want to avoid these products until a standard exists.

You may want to petition The American Petroleum Institute (API) to create a Standard. You can contact the API by going to http://www.api.org/contactus.cfm .

Good Luck