If you are concerned about u-bolts for piping, you can use MSS SP69 as standard. The only concern that I've heard voiced is the merits of round vs flat bar due some stress concerns.
I don't think any of the piping codes prohibit the use of u-bolts but a lot of companies and some states have rules and regulations for their use. I know that our company had rules on size, where, and what processes you could use u-bolts.
Probably 40%-50% of the orders for large u-bolts, especially alloy, are by print.
