Frequently Asked Questions

Q:  Does CentriPipe add structural integrity? Does it depend upon the thickness of the liner?

A:  CentriPipe is a true structural repair. The amount of structural reinforcement is determined by the final thickness of the liner. We typically design for fully deteriorated pipe. Pumping volume and retrieval speed ensures the proper thickness during application. Multiple passes are made to match the liner design thickness.

Q:  Are there adherence issues to rusted metal pipe? What if asphaltic coatings are encountered?

A:  PL-8000 liner has excellent adhesion properties and self-bonding properties but our design assumes no bonding whatsoever to the host pipe. This is designed as an additional factor of safety.

Q:  How do we address the issue of inlets or other pipes that may protrude into the main pipe?

A:  Drop inlet or other protrusions are removed or trimmed back flush to the main pipe to ensure an even application of mortar. They are sealed to the main pipe and temporarily plugged during the lining operation.

Q:  What is the cost to line corrugated metal pipe (CMP)?

A:  We focus on pipe diameters 30” and larger which may be round, elliptical, arched, square or similar. Costs will vary depending on access, flow diversion requirements, condition of the original pipe and liner thickness. We are pleased to provide estimates for specific information or projects.

Q:  What is the projected longevity of the new liner?

A:  The installed, seamless liner has the same life as new concrete pipe, but with the added advantage of much higher material strength that is free of any joints. The Army Corp of Engineers gives a design life to concrete storm pipe of 75 to 100 years.

Q:  Are steps taken to prevent contamination of the stream or storm water?

A:  Yes. Even though the process does not create any rebound or flow out of the pipe, erosion control socks are placed downstream as a precaution. There are no harmful chemicals leached from the liner materials.

Q:  What is the process used if the bottom of the pipe is completely missing or severely damaged?

A:  The bottom is restored before final lining using PL 12000. This is a very dense, high strength, fiber reinforced concrete that flows like self-levelling concrete to fill all voids under the pipe. This may be all that is needed in some pipe and PL 12,000 can be used to restore the invert prior to slip lining or cured-in-place lining.

Q:  What is the installed liner’s resistance to abrasion?

A:  Our material provides abrasion resistance greater than standard concrete because our products are at least twice as strong. For example, our prepackaged engineered product (PL 8000) has a compressive strength of 8,000 psi while standard concrete is typically 4,000 psi. PL 12000, which is used to repair the corroded base on corrugated metal pipe, has a compressive strength of 12,000 psi. Abrasion tests performed by CALTRANS on our materials exceeded their requirements.

Q:  What is the Manning n value of the pipe after the CentriPipe liner is installed?

A:  Manning’s n Coefficient: Based on field observations the projected “n” value will range from 0.013 to 0.020. We recommend that a conservative factor of 0.017 be used for calculations. In comparison, existing corrugated metal pipe has a value of 0.022.

Q:  Is the new cementitious liner affected by pollutants found in storm water?

A:  The lining material is resistant to dilute pesticides, fertilizers and petroleum products. The use of ConShield antibacterial additive can be used in the lining material when microbiologically induced corrosion is present.