Don’t Let Soft Foot Compromise Your Equipment

Soft foot can be one of the leading issues encountered in rotating equipment. It is also known as machine frame distortion and is a complex condition that can result in damage to the equipment, along with its output. These include quality and mechanical problems such as elevated vibration levels, misalignment, advanced wear and tear, premature metal fatigue and distortion, seals and bearing failure, and increased power consumption. We’ll show you everything you need to know about soft foot in industrial equipment below.

Soft Foot Causes

Looking to avoid or diagnose the condition? Soft foot can be caused by a number of issues including:

• Debris or dirt under the foot or feet.
• Bent, twisted, or warped base plates or machinery frames.
• Damaged or uneven equipment foundation.
• Bent or deformed shims.
• Excessive shims placed under a foot.
• Feet that are dented, twisted, warped, or otherwise damaged.
• Dirt or debris under the feet.

Types of Soft Foot

Parallel Soft Foot – This happens when the foot does not reach the base and creates a gap. Think of sitting in a chair with one leg shorter than the others. Parallel soft foot can be detected with a feeler gauge or dial indicator. Tightening the hold-down bolts can distort the machine’s frame.

Squishy Foot – Sometimes called spring foot, it occurs when the gap between the foot and base is filled with shims. The condition can distort the frame of the equipment as the foot is drawn down.

Angular Soft Foot – This occurs when the foot is touching the base on the inside or outside of the foot. However, part of the foot may be bent away creating an angle. Tightening the hold-down bolts can distort the machine’s frame.

Stress-Induced Soft Foot – It is difficult to detect this type of soft foot as it is caused by forces external to the machine. It may be caused by pipe strain, electrical connection stresses, misalignment, or other cause. Stress-induced soft foot can even occur during the alignment process Eliminating this soft foot can require more than one check.

Soft Foot Equipment Compromise

In addition to putting extra, undue stress on your machine, soft foot also causes performance issues. They include shaft movement as the result of the machine being tightened down. It can often lead to a 2x alternate current line frequency peak. This output is often indicative that soft foot is the issue as opposed to what most diagnose, imbalance or misalignment. Other signs of soft foot include frame and bearing house distortion, fretting corrosion, and internal misalignment.

Houston Dynamic Supply Soft Foot Diagnosis and Fixes

HDS has over 30 years of experience working with rotating equipment in many industrial applications. Our experienced team can provide solutions for your rotating pump including expert diagnosis and repairs. We work with all types of pumps, as well as offer OEM capabilities. HDS can perform visual inspection, non-destructive testing, disassembly, and other types of testing. Contact us today to learn more.