How much does it cost to weld the argon arc welding base of 219 stainless steel pipe and cover the welding port?

This depends on the diameter and wall thickness of your stainless steel pipe. I don’t know if the 219 you mentioned refers to the outer diameter. There is no 219 grade for stainless steel. To calculate how much a welding joint costs, you also need to know how many levels of radiographic flaw detection the welding joint you are welding can achieve. In my area, a first-class welder who performs 100% radiographic inspection will earn about 200 to 300 a day. If you accept private work, you can settle the bill according to the price of a single welding joint.