A Device for the Measurement of Head Loss across Pipe Coupons

Abstract

A bench scale device was developed to measure head loss across pipe coupons. Fully implemented, it will allow one to measure the effectiveness of a corrosion inhibitor in preserving or increasing the capacity of a water distribution system. Water service providers could conduct pilot tests of corrosion inhibitors and use this device to estimate · the resultant cost savings. Corrosion scales in water distribution systems increase pumping costs by at least $280 million annually (2003 dollars, based on Hatch, 1973). However, the true cost is probably much greater. In addition, this estimate does not take into account the substantial cost recovery which would result if corrosion inhibitors can remove corrosion scales from pipes. Pipe coupons are routinely used to monitor corrosion rates; however, this thesis proposes that they may also be used to monitor head loss due to pipe wall corrosion. The device holds the coupon in line with a closed conduit similar in shape to the coupon. This allows one to effectively "insert" the coupon into the conduit wall, and observe the decrease in flow that results. The decrease in flow indicates the head loss that occurs across the coupon. Device performance was tested using a clean aluminum coupon coated with sieved sand grains to simulate coupons of varying roughness. A model was developed to describe the observed flow as a function of coupon roughness and the elevation of water in the upstream tank. The observed flow was inversely proportional to the grain size of sand on the coupon. This suggests that results obtained from the device may be used to compare the head losses caused by two or more pipe coupons. Thus, coupons from two pilot distribution systems could be compared. Hence, one could determine if the corrosion inhibitors had limited the head losses. Plotting the total head loss coefficients versus relative roughness grouped by velocity for pipe coupons resulted in data sets that had positive and negative slopes. Although the majority of the data sets had positive slopes indicating total head loss coefficients increased with increasing roughness, a significance number of data sets had negative slopes. Hence, improvement of reliability and reproducibility of the device is warranted before the effect of roughness on total head loss of any one coupon could be reliably measured. However, the regression of the entire data set showed a positive relationship existed between roughness and total head loss. Consequently, improvement of the device and additional data collection according to a carefully planned experimental design is warranted before results could be directly applied to the pipes from which the coupons were taken. This would allow one to estimate changes in head loss due to the addition of corrosion inhibitors as well as associated changes in pump operating costs for a water distribution system.

Notes

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Thesis Completion

2005

Semester

Summer

Advisor

Taylor, James

Degree

Bachelor of Science (B.S.)

College

College of Engineering and Computer Science

Degree Program

Civil Engineering

Subjects

Dissertations, Academic -- Engineering; Engineering -- Dissertations, Academic; Corrosion and anti corrosives; Water pipes -- Corrosion -- Testing

Format

Print

Identifier

DP0022150

Language

English

Access Status

Open Access

Length of Campus-only Access

None

Document Type

Honors in the Major Thesis

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