Pipe Clamps
PT&P manufactures a range of standard clamps covering common pipe sizes. These are made of carbon steel and either painted, galvanized or left black. In addition, we frequently manufacture custom clamps for special applications. Examples of such applications are high temperatures requiring alloy steel, or applications requiring nonstandard dimensions.
PT&P normally analyzes such special designs using Finite Element Analysis (FEA). One reason for this is to ensure that the design has sufficient strength to support expected loads. This is also done to see if the clamp can be made more economically and still function satisfactorily.
FEA & Specially Designed Clamps
Recent examples include two Figure 80 type clamps for a high temperature application. Figure 80 clamps are heavy-duty three-bolt pipe clamps. Due to the high temperature duty, they were made from alloy steel, A387 Grade 91. This steel contains 9% Chromium, 1% Molybdenum and small amounts of Niobium and Vanadium. Both clamps are for 24” pipes, one for a load of 68,200 lbs., and one for 33,500 lbs.
Results: Clamp Test #1
The initial FEA was conducted on the clamp designed to sustain a load of 68,200 lbs. For this load, the PT&P Clamp Sizing program called for a clamp made from two 2” thick x 12” wide strips of steel. This case resulted in the FEA finding a maximum stress of 6150 psi. This is considerably less than
the allowable stress for the steel at the operating temperature. As a result, the clamp thickness was reduced to 1-1/2“. It was confirmed that the stresses were again below the allowable.
12 x 2” Clamp for 24” pipe with load of 68,200 lbs
Results: Clamp Test #2
The second FEA was conducted on a clamp designed for a load of 33,500 lbs. According to PT&P’s standard sizing program, this clamp’s design was made from 1-1/2” x 10” steel. The FEA found a maximum stress of 4250 psi, well below the 10,300 psi allowable. Thus, PT&P engineers reduced the size of the clamp to 1-1/4” x 8”, with resulting stress of 7331 psi.
1-1/2 x 10” Clamp for 24” pipe with a load of 33,500 lbs
Conclusions
In these analyses, it was assumed that the bending radius used to form the ears is 1.5 times the plate thickness. This value reflects the standard practice currently calculated and applied at PT&P. By comparison, AISC recommendations specify a bending radius of three times the plate thickness for plates ranging from 1 to 1-1/2 inches thick, and four times the plate thickness for greater thicknesses. The larger radii results in the use of more steel needed in order to accommodate the bolting arrangement.
While the Finite Element Analysis (FEA) results demonstrate that increasing the bend radius leads to lower stress levels in the formed components. These findings also show that the use of FEA at PT&P allows for accurate stress evaluation and design optimization, enabling the justification of reduced steel usage while maintaining structural integrity. As a result, this approach has led to significant cost savings for our customers.
From a piping system perspective, the performance of pipe clamps and supports is integral to compliance with ASME B31.1 and B31.3, which require that piping systems be adequately supported to safely sustain sustained, thermal, and occasional loads without overstress or excessive deformation. Pipe stress analyses performed in accordance with these codes assume that supports will provide the intended load-carrying capacity and restraint behavior throughout operating conditions. Finite Element Analysis (FEA) enables PT&P to verify that optimized clamp designs meet allowable stress limits at operating temperature while maintaining sufficient stiffness to support imposed loads without unintended redistribution or loss of restraint. When this analytical capability is paired with PT&P’s in-house manufacturing, designs can be validated, refined, and produced efficiently, ensuring that engineered assumptions are accurately translated into fabricated hardware. This integrated approach reduces design conservatism, shortens response time, and delivers code-compliant, cost-effective support solutions that align with the pipe stress model and the client’s overall project objectives.