The job of a pipefitter in the oil and gas industry can be a lucrative one. Depending on the amount of experience, annual salaries can climb well over $50,000. The job can also be a grueling one, however. And that’s especially true for those working in the southern states when the hot sun is beating down on them as they work to connect existing piping systems to new wells that are being drilled.
As any pipefitter knows, joining a new branch pipe to an existing main line involves a saddle cut, which is sometimes referred to as a fish mouth because the shape of the cut resembles the open mouth of a fish. The saddle cut is created to produce a T-shaped joint to join the branch pipe to the main pipe. Once the saddle has been cut and properly fit, the field weld can be executed.
The traditional method for making the saddle cut, however, is easier said than done. Back at the shop, pipefitters mathematically lay out the saddle on the pipe or use a paper template, a method of trial and error. For the latter, the paper template is wrapped around the pipe and traced with chalk. They then take a hand-cutting plasma torch or oxyfuel torch and slowly rotate the pipe, following the chalk line they created.
The process sounds simple, but because it’s cut by hand, it’s not always consistent, which requires a lot of grinding to make sure that the profile fits good enough to weld. Typically, though, one pass of grinding and fitting isn’t sufficient. And that’s where regrinding and refitting – and sometimes guessing – comes into play. Pipefitters will grind on the cut, hold it up to the main pipe and look for gaps and high spots, trying their best to make a tight fit while keeping the angle of the branch and length of the branch per print.
Depending on the skill of the welder and the pipe sizes, the process can take from 20 minutes to an hour and a half. At that point, the hot sun is only part of the concern; the money being lost is mounting exponentially.
Laying the groundwork
Since 1936, Mathey Dearman Inc. has been working to simplify the process of preparing pipes that need to be welded together. The company was founded by Chester Mathey, who was a machine builder by trade. Josh Wilson, the technical sales and application manager at Mathey Dearman, says that Mathey’s experience laid the groundwork for the 80-year-old company.
“The company’s roots were also laid by pipe welders and pipefitters, like Tim Dearman,” Wilson says. “That’s how we’ve come to really understand the oil and gas industry – from the ground up.”
Mathey Dearman’s inaugural products were primarily cutting and beveling machines as well as alignment and reforming clamp systems for tubes and pipes. Mathey’s latest product, the CNC Saddle Machine, carries on the founder’s goal to ease the task of those working with tube and pipe materials.
The CNC Saddle Machine is based on Mathey Dearman’s original Saddle Machine, a horseshoe shaped gear that runs in a track carrying a cutting torch around a piece of pipe to make cuts fast and accurately. The CNC version gives pipefitters the accuracy they need to reduce the process of producing shape cuts from more than an hour on average down to as little as five or six minutes.
“It gives a pipefitter the accuracy of computer-controlled technology, but in a simple-to-use format,” Wilson explains. “The picture-based software was designed to be easy to use for anybody, and traditional CNC code writing experience isn’t required. And then there’s the repeatability coupled with accuracy. You can accurately repeat that cut over and over again as opposed to doing it by hand where each cut is different.”
To make its cuts, the CNC Saddle Machine can accommodate standard straight barrel plasma torch sizes from all of the major brands that are used in North America, such as Victor, ESAB, Hypertherm, Miller and Lincoln. For international markets and barrel sizes that fall outside the standard range, Mathey Dearman offers several different sizes of torch holders and adapters.
Critical timelines
Although on-site manual cutting and grinding has been the traditional method for making saddle cuts that are ready to weld, some oil and pipe companies have outsourced their parts to fabricators with tube and pipe laser cutting capabilities. Relying on someone else’s timetable and equipment, however, can be problematic. And the myriad of requirements from oil and gas companies further compound that problem.
“We had a customer that was outsourcing its coated pipe for saddle cutting to a local fabricator,” says Wilson. “The pipes were coated for rust resistance, but the fabricator’s lasers couldn’t cut through the coating, which meant they had to sandblast the pipe and then perform the laser cut. If there was a lag in production, the pipes would start getting surface rust, so our customer would have to re-sandblast and then re-coat the pipe, adding additional cost and time to the schedule.
“They were constantly having to shuffle projects around, starting on one and stopping on another,” Wilson continues. “When they brought the process in-house, they regained control of the timeline, costs and the overall process.”
D&D Weld Fab Inc., a company that fabricates a range of high-pressure pipe products mainly for the oil and gas industry, is another customer that relies on the CNC Saddle Machine. Like many of Mathey Dearman’s customers, it once processed its pipes using paper templates. John Davidson, president of D&D, says there’s no comparison when it comes to the accuracy of the CNC Saddle Machine versus the old manual method.
“I can easily say that we’ve experienced an increase in productivity of 50 percent if not more,” Davidson explains. “Any time that you have to handle the pipe more than once, it starts eating into your profit. When I bid these jobs, I’m figuring on cutting it one time. Every time we have to rehandle it, it’s time and money that we’re losing.”
All of the welds that D&D makes have to be inspected using magnetic particle inspection, and they also have to undergo ultrasonic testing for quality. If two pipes don’t fit up properly, there’s a high risk for failing the QA/QC checks. As Davidson mentioned, D&D needs to get its welds done right the first time.
“Sometimes we’re delivering parts on a derrick boat that costs $250,000 per day, and you have the offshore crew that’s waiting on those parts,” Davidson says. “If we say we’re going to have it on Friday night, then that’s the expectation. If they don’t get it when they need it, the clock starts ticking and the costs start going up. With that one example, it’s no surprise that we’re incredibly schedule driven on everything we do.”
Hudson Mechanical Inc., a pipe welding outfit in Anderson, Calif., also put a Mathey Dearman CNC Saddle Machine to good work. The small fabrication company purchased its first CNC Saddle Machine when bidding a job to build a small bridge. Josh Estes, Hudson’s foreman, says the bridge required odd-angle saddle cuts in 4-in. pipe. Using the previous method would have cost the company a lot of time and, ultimately, a lot of lost revenue.
“In the past, we would lay out our branch connections ‘long hand’ using pipe coordinates and math,” he says. “After the layout process, we would make the cut and proceed with lots of grinding before achieving an acceptable fit.”
Estes says that Hudson primarily uses the CNC Saddle Machine for pipe branch connections, adding that its speed and accuracy allow the company to omit butt-welded tee fittings, replacing three butt welds with one branch connection.
Ample applications
Much of the work that D&D handles is done in-house at their fabricating shop, which is then shipped out to customers – who sometimes are literally out at sea. Working off of that scenario, Wilson says that the CNC Saddle Machine is just as useful out in the field as it is inside of a fabricating facility, like D&D’s as well as Hudson’s.
“Another niche of the market is smaller fab shops who may not have the capital to spend on a big stationary CNC machine or who may not have a building large enough to accommodate that type of equipment,” he says. “Those stationary CNC machines also require bigger forklifts or cranes to bring in the pipe, so there are a lot of logistical aspects to take into consideration. Our CNC Saddle Machine removes those requirements, providing the more automated cutting process they need without the additional resources, expenses and experience.”
Wilson says that on the flip side, the CNC Saddle Machine can complement the larger stationary CNC machines. When a stationary CNC machine is processing the larger-size pipe with its five axes and its longer cutting bed, smaller branch pieces like those for pressure vessel outlets or gauge weld-o-let connections, for example, could be processed on the Mathey Dearman CNC Saddle Machine.
“This could be pipe from 1 1/2 in. to 8 in. and all the way up to 12 in.,” Wilson says. “The bigger pipe can be processed on a stationary CNC machine and then the smaller pipe can be processed right inside the weld booths on the Mathey Dearman CNC Saddle Machine, removing the need to move the smaller pipe sections from one station to another. This also keeps them from tying up their half-a-million-dollar machines with smaller diameter pipe.”
So clearly, Mathey Dearman’s CNC Saddle Machine improves the ability of smaller fabricators to not only assist in meeting their tight delivery schedules but to also compete with larger organizations. As far as the larger organizations are concerned, pairing it with a stationary CNC machine gives them the opportunity to increase their efficiency while improving their overall output.
Mathey Dearman CNC Saddle Machine Case Study
Hill Mfg. & Fabrication: Oversees the fabrication of manifolds used for a wide variety of applications in the oil and gas industry.
Product Application:
CNC 1SA and 2SA saddle machines producing 77 manifolds on 10-in. pipe with 8-in. branches.
Production Requirements:
1. Five contour holes on the 10-in. pipe.
2. Two straight cuts of 37-degree beveled ends on the 10-in. pipe.
3. Five adjoining fish saddle cuts on the 8-in. branch pipe.
Previous Method:
- Purchased laser-cut pipe components with holes/profiles with a typical 14-day lead time.
- Cost for 10-in. pipe with five holes and beveled pipe ends totaled $580.
- Typical lead time for overall project, including receipt of components totaled 21 to 30 days.
Present Method:
- Mathey Dearman CNC Saddle Machine/Hypertherm Powermax 105 Plasma Machine for cuts.
- Purchase of raw uncut pipe.
Production Results:
- Overall production time of 14 days or less, a reduction of 14 days or more.
- Overall material cost of $365, a reduction of $215.
- Overall savings on 77 manifolds totaled $16,560 ($215 x 77).
