Page 199 - Pipeline Rules of Thumb Handbook

186 Pipeline Rules of Thumb Handbook

Hand-held computer determines concrete coating thickness

Technical data for the engineer’s file
Frank E. Hangs, Sovereign Engineering, Inc., Houston

Pipeline crossings, under water or in unstable soil, offer Computer program
many challenges to engineers.
Pipe is buoyant and an empty line may float in water. Wet The following program, written for the Hewlett Packard-
silts are like viscous fluids causing inadequately weighted 41CV (Figure 1), calculates the thickness of concrete weight
pipelines to pop up. There are various government entities coating for submarine pipelines expeditiously and with satis-
that have jurisdiction over navigable rivers, bays, marsh- fying results.
lands and offshore waters. These agencies may stipulate that The prompting feature (Figure 2) is employed to aid user’s
pipelines be buried at certain depths and be stabilized. data input. Important calculated values and a recap of
A good way to stabilize a pipeline is to use an adequate con- the inputs are printed out and each quantity is identified.
crete weight coating. Determining the thickness of the con- Thus, the tape is a complete record. The program is flexible
crete involves a process of balancing upward forces such as in that any inputs can be readily changed for a second run.
buoyancy of the mud and the downward forces—weights of Thus, many “what if” questions can be quickly answered.
pipe, protective coating and concrete, allowing a factor of sixty Suppose a heavier-weight pipe is used? What if the concrete
(negative buoyancy). Such computations with several vari- density is changed? If the negative buoyancy is reduced?
ables can become involved and tedious. Etc.

Figure 1. Hewlett Packard-41CV computer program.