Chrome-moly is an abbreviation for ‘chromium-molybdenum steel’ (sometimes spelled ‘cro-mo’ or ‘cr-mo’). Chrome-moly is a range of low alloy steels used, for example, to produce tubing for bicycle frames and race-car roll cages. It is not as lightweight as aluminum alloys, but has the advantages of high tensile strength and malleability, and is also easily welded. Although chrome-moly contains chromium, it does not have the corrosion resistance of stainless steel, though it does have a high tensile strength, and an excellent (high) weight to strength ratio.
As such, chrome-moly flanges, fittings, and pipe are not used in systems where abrasive compounds or chemicals are present, or where extremely high temperatures are found. However, their lower cost and great strength gives them a plethora of applications throughout the industrial and commercial markets. Water and sewage, pulp and paper, and natural gas all employ these types of metals.