A rather elaborate procedure (and involving special tools or projectiles) for pointing the internal joints of smaller steel water pipes is explained in Sec. 4.7.2.2.2 of AWWA C207. While I’m not sure the standard gets into the coordination or effects of welding (heat etc.) with wet or cured field mortar application, it does claim the line can be filled 24 hours after interior mortar application. It may be easier to hire a "little person", but maybe couldn't afford the salary and one also wonders about the safety liability nowadays!
[That being said, a lot of folks use instead factory cementlined ductile iron pipe systems, and particularly in these middle sizes, in that these systems neither require nor desire (to avoid these issues as well as maintain joint flexibility etc.) internal pointing of the joints.]
