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