Method of repairing a discontinuity on a tube by welding

A method for expanding the operating life of a tube having a discontinuity extending at least part way through its wall thickness, comprising the steps of:

• melting a portion of said tube in the area of said discontinuity to create a weld pool which comes in contact with said discontinuity and which reforms at least a portion of said discontinuity;
• adding an alloying material to said weld pool;
• allowing said weld pool to cool and solidify;
• analyzing the growth rate of said discontinuity before and after the alloying step;
• and determining the operating life of the tube based upon a comparison of the discontinuity growth rate.

A method for extending the operating life of a tube having a discontinuity extending at least part way through its wall thickness comprising the steps of:

• positioning an insert of said alloying material adjacent said inside surface of said tube;
• melting a portion of said tube, including melting a portion of said insert and said portion of the inside surface of said tube together, in the area of said discontinuity to create a weld pool which comes in contact with said discontinuity and which reforms at least a portion of said discontinuity;
• adding an alloying material to said weld pool;
• allowing said weld pool to cool and solidify;
• and then expanding said insert to be in essentially full contact with said tube after the step of melting.

A method for the repair of a tube having a discontinuity extending at least part way through its wall thickness, the method comprising the steps of:

• removing a vessel having a tube therein from service, the tube having a discontinuity extending at least part way through its wall thickness;
• inserting a welding head into said tube while said tube is in said vessel;
• operating said welding head to melt at least about 40% of the wall thickness of a portion of said tube in the area of said discontinuity to create a weld pool which comes in contact with said discontinuity and which reforms at least a portion of said discontinuity;
• operating a weld wire feeding means to deliver an alloying weld wire into said weld pool, thereby melting said wire and said portion of said tube together;
• allowing said weld pool to cool and solidify;
• and
• performing a nondestructive examination of said cooled and solidified weld pool.

A method for the repair of a tube having a discontinuity extending at least part way through its wall thickness, the method comprising the steps of:

• providing a tube comprised of nickel-base Alloy 600;
• providing a alloying weld wire comprised of a nickel-base alloy of the group Alloy 690 and AWS Class ERNiCr-3;
• inserting a welding head into said tube;
• operating said welding head to melt a portion of said tube in the area of said discontinuity to create a weld pool which comes in contact with said discontinuity and which reforms at least a portion of said discontinuity;
• operating a weld wire feeding means to deliver an alloying weld wire into said weld pool, thereby melting said wire and said portion of said tube together;
• and
• allowing said weld pool to cool and solidify.