Example 1: This example goes through the main design considerations for installing a pipeline using the S-lay method.
The main characteristics of the pipeline are give below
Water depth: 1500 m
Length : 100 km
Pipe outer diameter (OD): 14 inch (365 mm)
Wall thickness (WT): 25 mm
Design pressure : 400*105 Pa
Specified Minimum Yield Stress : 482 N/mm2
Expected undisturbed production rate : 3.6 km / day using single joint welding
Expected repair rate : 5 % of all welds
Average repair time : 20 minutes
Pipe joint length : 12 m
Coating : Corrosion protection

Q1: Calculate the lay rate.
The number of welds in one day is: 3600/12 = 300
The number of repairs in one day is: 0.05*300=15
The total time spent for repairs in one day is: 20 min x 15 = 300 min = 5 hours
Total: 3600/(24+5)= 124 m/h = 2980 m/day