On Mar 25, 9:51*am, Brian Whatcott wrote:

I am willing to accept that ERW is now as durable as cold drawn - the
type formerly preferred for racing car space frames 'n' stuff.....

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Dear Brian & Group,

I understand that has been the rule since 1 Jan 2000. It is one of
the reasons that the letters 'EMT' are no longer required to be
stamped on tubing meant for that market. That is, the raw sheet stock
is now of an acceptable alloy, and the ERW procedure used in turning
it into tubing now meets the same spec.

As for the use of ERW as a substitute for aviation-mild steel tubing,
that has been allowed since the 1950's when it's use was covered by a
CAM (?) notice.

-R.S.Hoover