If the US Government needs to make privately developed technical standards Federally enforceable, it will publish that information publicly. This includes some engineering standards. After they are referenced by the US Federal Code, they can be viewed. You can access these by the SIBR database or check out some of these pages:
This database provides information on standards that have been cited or incorporated by reference into the US Code of Federal Regulations (CFR). Includes information on how to obtain a copy of a standard. Alternatively, check with the standards publisher, a standards reseller or for a limited number of standards used in regulations, consult the American National Standards Institute (ANSI) Incorporated by Reference (IBR) Portal.
Standards Organizations that Offer Free Access to Their Standards