Published in Concrete Pumping magazine
The Sound Method of Predicting Pipeline Wall Deterioration
With concrete slamming its way through your pumping system under pressures of 1,500 psi, maybe 2,500 psi or more, it's not a question of whether the pipeline components will deteriorate, but how soon.
Pipe and components built specifically for the job of pumping concrete vary in strength according to the materials they're made of and the use for which they're intended. But even the sturdiest material will eventually give way to the extreme abrasiveness of pressurized concrete, especially at points along the line such as elbows and angles where the impact on inner walls is constant and severe.
If it hasn't already happened to you, just imagine the consequences of a rupture on the job site:
The point is that you want to know before you begin pumping that there will be enough pipe wall left to finish the job, either using the pipe you started with or by replacing pipe at scheduled safety intervals.
But how to predict how long your system's pipeline will hold up? Especially when there are so many variables at play? Variables such as: the nature of the aggregate in use; the speed of pumping involved; the amount of concrete to be pumped; the type of steel in the pipeline system; and, the configuration of the system in place (with all the bends and angles).
Suppliers of pipe can offer some guidance. The chart accompanying this article shows wall thicknesses required under certain pressures for different pipe diameters. While the chart thicknesses include a 3:1 safety factor, note that this is just a starting point. Even when brand new pipe is used, the recommendation is still that wall thicknesses be inspected on a regular basis. And when previously used pipe is to be used, this absolutely must be inspected before going on the job.
Many pumping companies have developed predictability programs in which they use ultrasonic gauges to measure, from the outside, the thickness of their pipe walls.
According to Bob Klemm, vice president of engineering with ConForms, Inc., a major supplier of pipe and accessories for concrete pumping:
"Ultrasonic testing is the only good way to measure pipe wall thickness. The alternatives used to be tapping with a hammer and judging by the sound, or weighing the pipe. These methods are unreliable and inaccurate.
"Today's pumps are high volume and high pressure. The old methods of testing are no longer acceptable. We recommend that customers frequently check their piping system with ultrasonic thickness gauges."
NDT International, Inc. of West Chester, PA, offers a hand-held, high-precision ultrasonic thickness gauge for less than $1,500. Called the NDT Model 710, this battery-powered instrument spot-measures thicknesses of 0.030" to 9.999" in easy-to-read LCD display.
Since the Model 710 is capable of measuring thickness even when concrete is gushing through the pipe, it's being used by pumpers (1) before they begin a job to determine in advance the condition of the pipe and then (2) during pumping to establish a wear-rate.
"One way pumpers can do this," says Vic Kelly, president of NDT International, "is to spot check early on, let's say after 5,000 cubic yards have been pumped. If at that point a 0.40" wall at an elbow has diminished to, say, 0.38", you can calculate if and when the pipe should be replaced, based on a projection of the total yardage to be pumped."
(It should be noted, though, that with "dual-wall" pipe construction . . sometimes referred to as "pipe-within-a-pipe" . . an ultrasonic thickness gauge cannot determine the amount of wear to the inner wall.)
NDT claims that the Model 710 is accurate to 0.001". It works in temperatures from 10ïÀ„ to 120ïÀ„ F. and its portability allows for easy checking along the pipeline. Little in the way of operator training is required.
Over time, the investment in an ultrasonic thickness gauge will pay off, not just in preventing on-job disasters but in helping to determine which type of pipe is the more efficient buy for a particular application.
NDT International has been a manufacturer of industrial-quality gauges since 1971. For more information and a no-obligation personal consultation, contact Mr. Vic Kelly, NDT International, Inc., 711 Creek Rd., West Chester, PA 19382 Phone: (610) 793-1700 Fax: (610)793 1702
Pipe and components built specifically for the job of pumping concrete vary in strength according to the materials they're made of and the use for which they're intended. But even the sturdiest material will eventually give way to the extreme abrasiveness of pressurized concrete, especially at points along the line such as elbows and angles where the impact on inner walls is constant and severe.
If it hasn't already happened to you, just imagine the consequences of a rupture on the job site:
- the potential for injury to personnel in the area
- the possible damage to property
- the waste of material
- the clean-up effort
- the environmental consequences
- the expense of replacing the damaged section and cleaning out the system
- the lost man-hours
The point is that you want to know before you begin pumping that there will be enough pipe wall left to finish the job, either using the pipe you started with or by replacing pipe at scheduled safety intervals.
But how to predict how long your system's pipeline will hold up? Especially when there are so many variables at play? Variables such as: the nature of the aggregate in use; the speed of pumping involved; the amount of concrete to be pumped; the type of steel in the pipeline system; and, the configuration of the system in place (with all the bends and angles).
Suppliers of pipe can offer some guidance. The chart accompanying this article shows wall thicknesses required under certain pressures for different pipe diameters. While the chart thicknesses include a 3:1 safety factor, note that this is just a starting point. Even when brand new pipe is used, the recommendation is still that wall thicknesses be inspected on a regular basis. And when previously used pipe is to be used, this absolutely must be inspected before going on the job.
Many pumping companies have developed predictability programs in which they use ultrasonic gauges to measure, from the outside, the thickness of their pipe walls.
According to Bob Klemm, vice president of engineering with ConForms, Inc., a major supplier of pipe and accessories for concrete pumping:
"Ultrasonic testing is the only good way to measure pipe wall thickness. The alternatives used to be tapping with a hammer and judging by the sound, or weighing the pipe. These methods are unreliable and inaccurate.
"Today's pumps are high volume and high pressure. The old methods of testing are no longer acceptable. We recommend that customers frequently check their piping system with ultrasonic thickness gauges."
NDT International, Inc. of West Chester, PA, offers a hand-held, high-precision ultrasonic thickness gauge for less than $1,500. Called the NDT Model 710, this battery-powered instrument spot-measures thicknesses of 0.030" to 9.999" in easy-to-read LCD display.
Since the Model 710 is capable of measuring thickness even when concrete is gushing through the pipe, it's being used by pumpers (1) before they begin a job to determine in advance the condition of the pipe and then (2) during pumping to establish a wear-rate.
"One way pumpers can do this," says Vic Kelly, president of NDT International, "is to spot check early on, let's say after 5,000 cubic yards have been pumped. If at that point a 0.40" wall at an elbow has diminished to, say, 0.38", you can calculate if and when the pipe should be replaced, based on a projection of the total yardage to be pumped."
(It should be noted, though, that with "dual-wall" pipe construction . . sometimes referred to as "pipe-within-a-pipe" . . an ultrasonic thickness gauge cannot determine the amount of wear to the inner wall.)
NDT claims that the Model 710 is accurate to 0.001". It works in temperatures from 10ïÀ„ to 120ïÀ„ F. and its portability allows for easy checking along the pipeline. Little in the way of operator training is required.
Over time, the investment in an ultrasonic thickness gauge will pay off, not just in preventing on-job disasters but in helping to determine which type of pipe is the more efficient buy for a particular application.
NDT International has been a manufacturer of industrial-quality gauges since 1971. For more information and a no-obligation personal consultation, contact Mr. Vic Kelly, NDT International, Inc., 711 Creek Rd., West Chester, PA 19382 Phone: (610) 793-1700 Fax: (610)793 1702