The "belling tool" works by hydraulically inserting a lubricated mandrel into one end of the pipe under hydraulic pressure. The mandrel is shaped to leave a bell shaped pipe end with a uniform taper and with a short lead in flare. A lubricant is used to prevent galling between the mandrel and the pipe which is caused to yield and form the "belled" shape.

After "belling" the lubricant is removed and the soundness of the "belled" end is checked by a technician. Additional inspection using magnetic particle equipment can also be done and is recommended where the steel line pipe expansion strain is larger than 10 percent. A careful quality control process is used to check that mandrel tolerances are met and that after "belling" there is no galling of the pipe surface and no splitting or cracking of the pipe has occurred.

The "pinning tool" shapes the other end of the line pipe by shaping the leading edge of the "pin end" and a creates a groove behind this which forms a shallow reservoir to hold "Zapoxy" used as a lubricant during the joining process. There are two pin end shapes that can be made. The type 2 pin end is used for bare or unlined pipe and the type 4 "pin end" used for internally lined pipe. The type 4 "pin end" has an increased taper to allow the internal coating to cover the bevel and to extend to the outside surface of the pipe.

The video above shows how the "Belled" and "Pinned" line pipe is joined in the field for an onshore pipe lay project. Two items of equipment will be supplied by Swiftpipe to site which is the Zapoxy mixing unit and the Zap-Lok® Press.

The Zap-Lok® Press is supported and moved using a side boom tractor crane and is operated by a trained technician. A thin layer of "Zapoxy" which is a lubricant and sealant is applied to the full circumference of the belled and pinned ends prior to joining. This is a manual process so that the technician can inspect the pipe ends again just before joining. The belled and pinned ends of the pipe are inserted into the Zap-Lok® Press and under controlled hydraulic pressure the pin end is forced into the belled end. The depth of insertion is pre marked on the pin end and is controlled by the technician. The pin end acts as a mandrel and causes the belled end to expand further. After joining the belled pipe end clamps the pin end with huge forces. During the joining process the Zapoxy lubricates the insertion of the pin end and is extruded leaving a steel to steel connection inside the pipe.

After the joint is completed and checked the Zap-Lok® Press and support equipment is moved along to the next joint. The joining process takes less than two minutes to complete including the equipment move to the next joint. A pipe lay speed of over 1000 feet per hour has been achieved using this process. A team of only 7 operatives are needed in the field per shift to achieve this. The Zap-Lok® process produces a strong permanent joint which can be used in the same pressure service as welded lines. Thousands of miles of line pipe have been joined in the US using Zap-Lok® as testament to its efficiency and reliability.

The video above shows the Zap-Lok® system in operation on a barge in the Gulf of Mexico. The Zap-Lok® press is skid mounded and the footprint required for the equipment including the Zapoxy mixing machine is small allowing line pipe which has already been prepared for Zap-Lok® joining to be stored on the barge before use. Pipe lay rates of 18-30 joints per hour with a maximum 39 joints per hour were achieved from the barge working in 160 ft (49m) water depth on a 32.4 mile (52kms) pipe lay project. The operation of the Zap-Lok® press is similar to onshore use except the Zapoxy mixture is varied for offshore use as it will be laid in water and the curing time is adjusted.

Multiple lines can be laid offshore simultaneously using several Zap-Lok® presses, as shown in the photo below.