# API RP 1102 Calculator User Guide

The web-application performs stress calculation for Steel Pipelines crossing Railroads and Highways as per API RP 1102. This design methodology relates to steel pipelines installed using trenchless construction methods, in particular auger boring, with the crossing perpendicular to the railroad or highway. The design performed by the web-application for the steel pipeline crossing is applicable in all scenarios where provisions of API RP 1102 code are applicable (refer clause 1.2 of API RP 1102) except the following:

• Two types of unit systems i.e. SI Unit & Customary Unit system can be selected for performing the calculation.
• The design methodology used in the program is such the pipelines having diameters of D = 2.375 to 48 inches (60.3 to 1219 mm) can be analysed. Values from various graphs of API RP 1102 for pipe diameter greater than 42 inch (1067 mm) is obtained by extra-plotting the graphs.
• The wall thickness to diameter ratios must be within the range of tw/ D = 0.010 to 0.080.
• Railroad crossings can be analysed for depths of cover H = 6 to 14 ft (1.8 to 4.3 m). Highway crossings can be analysed for depth of cover H = 3 to 10 ft (0.9 to 3.0 m).

### Design Methodology

The methodology is broadly divided into four parts for designing railway or highway crossing of steel pipelines as per API RP 1102:

1. Calculation of circumferential stress due to internal pressure by "Barlow formula" and check against allowable.
2. Calculation of stresses due to external loads such as:
a)   Stresses due to Earth Load
b)   Stresses due to live load
- Impact Factor
d)   Highway Cyclic Stresses
3. Calculation of principal stresses, effective stress and check against allowable
4. Check for fatigue

### List of Symbols/ Terms

Bd
Bored diameter of crossing
Be
Burial factor for circumferential stress from earth load
D
Pipe outside diameter
E
Longitudinal joint factor
E'
Modulus of soil reaction
Ee
Excavation factor for circumferential stress from earth load
Er
Resilient modulus of soil
Es
Young’s modulus of steel
F
Design factor (barlow stress & fatigue check)
Fa
Allowable design factor (equivalent stress check)
Fi
Impact factor
GHh
Geometry factor for cyclic circumferential stress from highway vehicular load
GHr
Geometry factor for cyclic circumferential stress from rail load
GLh
Geometry factor for cyclic longitudinal stress from highway vehicular load
GLr
Geometry factor for cyclic longitudinal stress from rail load
H
Depth to the top of the pipe
KHe
Stiffness factor for circumferential stress from earth load
KHh
Stiffness factor for cyclic circumferential stress from highway vehicular load
KHr
Stiffness factor for cyclic circumferential stress from rail load
KLh
Stiffness factor for cyclic longitudinal stress from highway vehicular load
KLr
Stiffness factor for cyclic longitudinal stress from rail load
L
Highway axle configuration factor
LG
Distance of girth weld from centerline
p
Maximum allowable operating pressure
NH
Double track factor for cyclic circumferential stress
NL
Double track factor for cyclic longitudinal stress
Nt
Number of tracks at railroad crossing
Ps
Pt
R
Highway pavement type factor
RF
Longitudinal stress reduction factor for fatigue
Seff
Total effective stress
SFG
Fatigue resistance of girth weld
SFL
Fatigue resistance of longitudinal weld
SHe
SHi
Circumferential stress from internal pressure
SHi(Barlow)
Circumferential stress from internal pressure calculated using the Barlow formula
S1
Maximum circumferential stress
S2
Maximum longitudinal stress
S3
SMYS
Specified minimum yield strength
T
Temperature derating factor
T1
Installation temperature
T2
Operating temperature
tw
Pipe wall thickness
w
Applied design surface pressure
αT
Coefficient of thermal expansion
γT
Unit weight of soil
SHh
Cyclic circumferential stress from highway vehicular load
SHr
Cyclic circumferential stress from rail load
SLh
Cyclic longitudinal stress from highway vehicular load
SLr
Cyclic longitudinal stress from rail load
νs
Poisson’s ratio of steel