Stevenson4472
Civil/Environmental
Our public water agency's construction specifications for mortar lined welded steel pipe (with gasketless welded joints, both full penetration butt welded and welded bell and spigot) require that the contractor fill the gap in the shop applied mortar lining of the two pipe segments (consistent with AWWA C-205, Section 4.7). Completing the interior mortar coating of joints in pipe greater than 24-inches is easy because they can be accessed manually from inside the pipe where the mortar is applied by trowel. Smaller pipe presents a practical problem. The method for completing the mortar inside the smaller pipe joint is to "butter" the inside of the joint, push the pipe ends together (seat the pipe if bell and spigot), and then pull a burlap wrapped ball through the joint which forces the mortar up into the joint creating a seamless mortar lining at the joint between the shop applied mortar lining of both pipe segments.
The practical problem is that there is always a need to weld the joint shortly after the pipe ends are mated, particularly when pushing the pipe through a casing which is a mostly continuous operation. The need to promptly weld the pipe ends is particularly important for full-penetration butt welded joints since the pipe ends are not stable until welded. Becuase the mortar in the "buttered" area inside the pipe will set before the weld can be completed, one cannot wait to mortar the joint until after the weld has been completed and cooled before pulling the ball to complete the mortared joint. If you pull the ball prior to welding, the mortar will seep up through the gap between the pipes and would need to be chipped or ground away from the gap which is to receive the full-penetration butt weld.
Has anyone had experience with completing the inside mortar on small diameter welded steel pipes? How have you done it? Have you tried rapid setting mortar on bell and spigot joints (so that the mortar can set quickly enough for the joint to be welded within, say an hour)? How long must one wait until the joint can be welded using a standard AWWA mortar mix? How can smaller butt welded joints be mortared at all? Any insight would be appreicated.
The practical problem is that there is always a need to weld the joint shortly after the pipe ends are mated, particularly when pushing the pipe through a casing which is a mostly continuous operation. The need to promptly weld the pipe ends is particularly important for full-penetration butt welded joints since the pipe ends are not stable until welded. Becuase the mortar in the "buttered" area inside the pipe will set before the weld can be completed, one cannot wait to mortar the joint until after the weld has been completed and cooled before pulling the ball to complete the mortared joint. If you pull the ball prior to welding, the mortar will seep up through the gap between the pipes and would need to be chipped or ground away from the gap which is to receive the full-penetration butt weld.
Has anyone had experience with completing the inside mortar on small diameter welded steel pipes? How have you done it? Have you tried rapid setting mortar on bell and spigot joints (so that the mortar can set quickly enough for the joint to be welded within, say an hour)? How long must one wait until the joint can be welded using a standard AWWA mortar mix? How can smaller butt welded joints be mortared at all? Any insight would be appreicated.
