Algor Software Enables Engineers to Re-design Pipe Shoes

Shown here is the first Algor analysis the engineers at Piping Technology & Products performed on the pipe shoes. The analysis revealed high levels of stress in the rib area.

There may be miles of piping systems in an industrial plant, transporting toxic liquids between stages of a chemical or industrial process. One leaking pipe can cost companies thousands of dollars, endanger workers' lives and even threaten surrounding communities.

The makers of the piping systems have little room for error. That's why Piping Technology & Products, Inc. uses Algor's sophisticated engineering software to design and analyze piping systems its customers build for power plants, petroleum refineries, paper mills and other industrial facilities.

Piping Technology & Products is a Houston-based company which designs and manufactures industrial piping systems primarily for the power, petroleum and paper industries. Its clients include major engineering and industrial companies with projects worldwide.

"In most industrial plants, piping systems travel throughout all areas of a plant," said Senu Nagappan, lead engineer at Piping Technology & Products. "We design and analyze these systems before they are built, and we analyze existing systems to locate points of vulnerability that need to be repaired."

In one instance, an engineering and construction company came to Piping Technology & Products with an order for a pipe shoe for a 30 inch pipe. Pipe shoes are external attachments to pipes which support a pipe from the bottom.

In this instance, the pipe shoes had to be strong enough to withstand the vertical and horizontal stresses that occur during operation caused by heat, vibration, weight and pressure. Using Algor's Integrated Plant Package (IPP), the engineers analyzed the design of the current pipe shoes to see if they needed to make any modifications.

"We performed a linear stress analysis which showed that the stress would be 37,630 pounds per square inch (psi)," said Nagappan. "This amount proved that the shoes would be over-stressed since the range of stress for the shoes should have been 21,600 psi."

The engineers studied the analysis results and concluded that the stresses were caused by the bending of the shoe base on the round beam on which it is welded. The Piping Technology & Products engineers proposed three options for making the design meet the stress requirements:

1. Add four brace gussets below the saddle portion of the pipe shoes to relieve the high stress in these areas.
2. Add two extra ribs in the length of the shoe base to relieve the high stresses by distributing the load.
3. Modify the saddle portions to create one large saddle which runs the entire length of the shoe, distributing the load and thus relieving the stresses.

"Knowing exactly where the stresses were located, we were able to make an informed decision about optimizing the design of the shoes to meet the required stress levels," said Nagappan.

The engineers chose the second option and added two extra ribs in the shoe base to provide additional reinforcement to the single rib in the original design. This modification was more cost-effective and simpler for the client.

Based on the information provided by Algor analysis, engineers added two extra ribs to optimize the design of the pipe shoes.

The final Algor stress analysis revealed that stress was significantly reduced by adding the two rib structures.

"By adding the new ribs, we decreased the stress to 14,680 psi which is well below the allowable stress levels for the shoes," said Nagappan.

"IPP analyzes the particular types of stress that occur in piping systems," said Nagappan. "Although pipe shoes may look similar to a part in a mechanical system, the types of analyses we perform on the shoes are quite different from what mechanical engineers would perform on a plastic or metal part. Because IPP was able to analyze the factors related to piping systems, we were able to create the ideal design for the new shoes."