The Pipe stress analysis is an important process in the design of pipelines, after tracing the route, following the design guidelines, it is verified by means of a stress analysis that the pipe works without problems during its life, taking into account the standard that applies according to the codes.

These studies take into account physical phenomena such as thermal expansion, the weight of the pipe, weight of the fittings and supports; when these pipes enter into operation they cause stresses that damage some supports, nozzles, restrictions and generate torsion in some cases. All these events are verified in an analysis and compared with the ASME code taking into account the pipe material and the process conditions of the system; it is the basis to make a flexible solution proposal.

In conclusion, a stress analysis is a static study that calculates the stresses suffered by the pipes and fittings; these stresses are internal and are compared against the maximum allowable stresses of each material at the process conditions. Additionally, it calculates the forces and moments that the pipe generates at the points that restrict, for example, supports and nozzles. With this information, the system designers design the structures that will support the piping system and verify if the nozzles are sufficiently resistant to the forces and moments that are reaching them.

Advantages of a flexibility study for a pipeline:

• Avoid cost overruns due to poor selection.
• Limits the loads on nozzles of connected equipment within allowable values.
• Avoids pipe buckling.
• Optimizes pipe runs and the number of flexible elements.
• For lines with the same characteristics only one analysis should be made.

The software used by us for pipe analysis is CAESAR II, which is based on the ASME code and is classified according to the fluid being handled.

The design standards are:

• B 31.1 Power piping and steam systems.
• B 31.3 Process piping.
• B 31.4 Liquid hydrocarbon transport.
• B 31.8 Gas transmission and distribution piping.
• ASME BPVC (Section II, V, VIII). General requirements.

Design and calculation of expansion joints:

EJMA (Expansion Joints Manufacturers Association).

Steam turbines:

• NEMA SM 23. (National Electrical Manufacturers Association).

Pumps, compressors and other equipment:

API Standards.

Standards for calculation and design of supports are also involved:

• MSS SP 58.
• MSS SP 69.
• MSS SP 89.

Flexilatina of Colombia has wide experience in different fields of the industry at national level and part of Latin America in which it has carried out different studies for projects in sugar mills, thermal plants, textile plants, power generation plants by means of steam turbines and in some cases gas turbines, among others.

Some of the industries where we have participated with our studies are the sugar, paper, power generation, steel, chemical, petrochemical and Oil & Gas industries; to companies such as Prime Termoflores, Brinsa, Termoguajira, Compañía Eléctrica de Sochagota, Bioenergy, Ingenio del Cauca, Ingenio San Carlos, Ingenio Providencia, Manuelita, Propal, Smurfit Kappa and Termosierra.

We make the difference for our extensive experience of more than 30 years in selection and manufacturing of flexible elements to solve the problems detected in a stress analysis.

Image 1. General isometric.

Image 2. Max. stress in the pipe run (color coded).