Tech Notes

These documents are single page technical briefs based on common questions received by the clay pipe industry.  For more detailed information, Contact NCPI's Technical Representatives.

Abrasion Resistance of Sewer Pipe Materials - TN17

The abrasion resistance of several commonly used sewer pipe materials.


Bell or Coupling Holes and Shovel Slicing - TN15A

The digging of bell or coupling holes and shovel slicing of the initial bedding in haunch areas of the pipe are two critical functions that need to be part of any successful sewer pipe installation. ...


Classification of Soils - TN18

Soil classification using the U.S. Bureau of Reclamation method.


Curvilinear Sewers - TN12

New factory applied joints provide angular deflection enabling installation of curved sewers.


Deflection: Does it Matter? TN06

This edition of TECH NOTES, considers two aspects of flexible pipe deflection: Structural Design and Hydraulic Performance.


Infiltration and Inflow Studies - What do they really show? - TN05

Early clay pipe lines were often designed to allow infiltration and inflow not only to dilute sewage, but to aid in its flow downstream.


Is Less Really Less - An Economic Approach to Sewer Pipe Selection - TN04

When comparing alternate bids of pipe with different life expectancies, the lowest initial bid is not always the best bid or in the best interest of the owner. The goal is to select the pipe material...


Knowing Your Limitations - TN14

Television has been growing in popularity as a means of investigating the condition of all types of buried sewer lines. As an investigative tool, the latest equipment is unmatched in enabling operato...


Modern Clay Pipe Joints: No Longer a Case of Leaks and Root Intrusion - TN21

Leaky joints were common from the earliest use of drainage pipe to convey waste. That in itself was not considered a problem. Why? Treatment of the effluent was very primitive or non‐existent. D...


NCPI/NYC Research Project - TN25

NCPI/NYC Research Project - An Evaluation of Four Bedding Systems. The City of New York places a high priority on achieving the longest life cycle possible for all sewer installations while reducing ...


Sand as a bedding material - TN11

Sand has been used as a bedding material in parts of the country for many years and has been presumed to be the ideal bedding material. The limitations of sand bedding are presented.


Surcharge Fills - TN24

There is often considerable uncertainty about the ability of an existing sewer to support additional backfill placed over the top of the original trench. The following suggestions may be useful to th...


The Decision is Yours - TN10

Selecting a particular sewer pipe material may affect the lives and pocketbooks of the people in your community for the next 100 years or more.


Vitrified Clay Pipe - The Choice for Difficult Solutions - TN08

When clay pipe is vitrified, the clay mineral particles become fused into an inert, chemically stable compound, integrally bonded by its very nature, independent of any artificial bonding agent.


Vitrified Clay Pipe and Polyvinyl Chloride Pipe - TN07

An Environmental Comparison of VCP and PVC.