Web crippling behavior of cold-formed duplex stainless steel (CFDSS) lipped channels with unfastened and fastened flanges was experimentally investigated. Totally, 22 tests were conducted under codified interior-two-flange (ITF) loading condition as per American Specification for the design of cold-formed stainless steel structural members. Test results of the CFDSS lipped channels with unfastened and fastened flanges were obtained and compared. It is revealed that flange conditions significantly affected the web crippling strengths of lipped channel sections, especially for those with relatively larger web slenderness ratios. The obtained web crippling strengths were used to assess the suitability of codified web crippling design provisions in the recent update American Specification. It is found that the codified design provisions generally overpredict the web crippling strengths of the CFDSS lipped channels and result in unconservative predictions. Reasons of the unsatisfactory predictions by the design specification are discussed.