Page 200 - Pipeline Rules of Thumb Handbook

Corrosion/Coatings 187

Nomenclature and storage registers inputs

Reg. no.
05 T = Concrete thickness, in. Assume trial
value. Final answer is cumulated in
Reg. 0.5.
15 D = Pipe diameter, in.
16 WP = Weight of pipe, lb/lf.
17 TH PC = Thickness of protective coating. Usu-
3
ally /32 in. or 0.0938in.
19 DC = Density of concrete, lb/cuft. Usually
140, 165, 190.
20 DM = Density of mud or fluid, lb/cuft. River
mud is around 90.
18 DPC = Density of protective coating, lb/cuft.
95 is average.
21 T INCR = Increment of T. Decimal of in. 0.125 is Figure 2. Most common questions asked when checking
coating buoyancy.
suggested for numerical precision—
not that a tolerance of this order can
2
be constantly achieved in the pipe VT = ( D+ ( 2 THPC)+ 2 T) 0 0055
.
coating world. Increment can be made
)(
smaller, if desired. WMD = ( VT DM)
11 NEG BUOY = Negative buoyancy. Desired minimum
value, lb/lf. Can be 0 in special cir- Note: User is encouraged to employ most reliable and suit-
cumstances—e.g., to ascertain if a able data available; such as density of protective coating, mud,
given pipe will float in water, or will a concrete, etc.
certain coated pipe sink in mud?

Examples
Each value keyed in is printed on the tape as a check of
inputs and the program prompting feature queries user for
Put program into calculator, XEQ Size 30. The printed
value of next named input (Figure 2).
RESULTS-RECAP portions of each of three examples are
given. When the user XEQ “CONC” and inputs the data from
the lower part of the tabulation, he will get the same calcu-
Calculated values lated values above.
Figure 2 includes the most common questions asked when
Reg. no. checking coating buoyancy. Always be sure flag 01 is clear
06 WPC = Weight of protective coating, lb/lf. XEQ “CONC” and put in new trial T and R/S. Also R/S
07 WC = Weight of concrete coating, lb/lf. after all other inputs. After all prompted data are keyed in,
08 WT = Total weight—pipe and coatings, lb/lf. the processing starts and results are printed out. Notice
09 WMD = Weight of mud (fluid) displaced, lb/lf. T = 4.6250in. has an actual negative buoyancy of 25.1843. If
10 WT-WMD = Actual negative buoyancy, lb/lf. T = 4.5in. the actual negative buoyancy = 18.4510 which is
12 VT = Total volume displaced by pipe and less than 20. Precise solution is between 4.5in. and 4.625in.
coatings, cuft/lf. If user wishes to find T which produces an actual nega-
1
13 BULK DEN = Bulk density, wt/vt. lb/cuft. tive buoyancy nearer 20: STO 4.5 in RO 5, STO /16 in.
14 SP GR = Specific gravity, bulk den/den water. (0.0625in.), in R21, XEQ 01. This produces T = 4.5625 where
actual negative buoyancy is 1.8113 greater than 20. This
refinement can be found in choosing small T INCR. Note
weight of concrete coating is now 471.8269lb/lf and we have
Formulas approached closer to 20.

))(
WPC = ( D+( THPC THPC) 0 0218 ( DPC) Calculated values. Weight of protective coating and con-
.
crete, total weight and volume of pipe and coatings per linear
WC = ( D+ ( 2 THPC)+ ) 0 0218 ( DC) foot will be of value in transporting coated pipe, etc.
T T
.