Dear All,
We are providing resident engineering services for a cable-stayed rail bridge construction in a zone of high seismic activity. My question is regarding welding. We are at a point where steel pile cap is going to be welded to the top of accurately cut 2500-mm diameter steel piles under water. Welding will be performed 2.5 meters below sea level. Weld type specified for this connection is complete joint penetration groove weld. Contractor wants to do the welding from one side only without using a backing bar - from the inner side of piles, where we prefer this type of weld to be done from both sides, K-type groove weld. We are worried about the quality of this critical weld if done from one side only without a backing bar. Contractor does not want to build a cofferdam that will house all of the nine 2500-mm diameter piles that are spaced at 6.0 meters o.c., in a grid that is 3x3. He'd rather build an individual cofferdam for each pile. Our concern is that the inflatable gasket may not work properly and water may penetrate into the weld zone endangering the quality of the weld. Is there any technical information or reference in standards that recommends complete joint penetration groove weld to be done from both sides in a case like this one?
Thank you everyone,
Ozan Ustundag, PE