The Sag machine comes equipped for 8 inch pipe. Additionally, we build adapters for 10 and 12 inch pipe as well. Sags in 12 inch pipe can be slow and difficult to remove.

Sags on larger diameter pipe are harder to remove. In order to remove a Sag, the machine has to bend the pipe. Larger pipes have more strength and are more difficult to bend within the span of the sag machine. In addition, larger diameter pipe bends in a longer radius, so more length has to be lifted at the same time. As this length increases, it gets farther from the vibrator.

The success rates vary with the customer and their job conditions. It is important that the pipe is surrounded with a granular material (crushed rock or sand) and the material is saturated with water or water is added as shown in the detail on the web site.

The sag machine typically works well where the pipe is deep and the water table is above the top of the pipe. Most customers report success rates of 90 to 100 percent in these conditions with 8 inch and 10 inch diameter pipe.

The machine also has a high success rate in dry conditions where water is injected and the granular pipe zone material contains fines.

Where water is injected in dry conditions and the pipe zone material is coarse or the fines are screened out, the success results are more mixed. We think this could be from the material being too free draining in proportion to the amount of water that was applied and not enough water was retained.

Where the machine has been used in dry conditions without adding water, the results have usually been poor. In most cases the machine will not work dry, although some customers have reported examples where they had success in dry conditions. Most experienced users tell us that if they do not see results immediately, they start injecting water.

Water helps lubricate the pipe zone material to flow underneath the pipe. Also, water helps transfer the vibration out into the surrounding material. In dry conditions, we have seen the pipe lift, but go back down when the lift pressure was released.

There may be conditions specific to certain sites that affect the results.

Removing a Sag will vary with different conditions. Most experienced users tell us that it takes them about a half of a day to set up and remove a typical minor sag.

When assembling the machine sections inside a manhole, it may be necessary to chip out part of the channel to allow the sections to align and bolt together. This may take more time if it is not done in advance.

No. The machine does not work upside down. It would be necessary to feather out the belly on the upstream side of the hump.

You will need a 75 CFM or larger air compressor, a 3/4 inch minimum diameter air hose, and our air swivel, oiler & filter assembly. You will also need a separate 3/8 inch air hose to activate the lift mechanism. It is possible to pull the machine and hoses by hand, but it is too much work for most people unless the sag is close to the manhole. We recommend using a light duty winch or pulling device to move the machine with rollers or pulleys at each end of the pipe. A pull back line should be attached in case the machine gets stuck. A TV camera will be necessary unless the sag is near a manhole.

We don't think any special training is necessary. Most customers have been doing fine by following the instructions. We can answer any questions by phone if they arise. Like learning to operate any other equipment, one should go slow and careful until they have some experience.