A　direct　route　by　combining　the　PWC(plastic　work　curvature)　criterion　and　the　nonlinear　FEA　technology,　was　adopted　to　calculate　the　plastic　internal　pressure　and　the　plastic　piping　loads　of　an　industrial　header　product,　and　the　calculated　results　were　compared　with　that　of　other　methods.　The　comparisons　show　that　the　PWC　plastic　pressure　load　results　of　perfect-plastic　analysis　are　very　close　to　the　Cloud-Rodabaugh　limit　pressure　result　and　the　ASME　limit　pressure　result;　the　PWC　plastic　loads　are　characterized　by　reflecting　the　structural　strengthening　effect　of　the　material　strain-hardening　on　the　header　by　using　the　plastic　work　as　the　global　indicator　of　plastic　collapse　mechanism,　and　avoids　the　arbitrary　of　users＇　experience　to　select　an　appropriate　deformation　parameters　for　determining　the　TES(twice　elastic　slope)　plastic　loads;　the　direct　route　is　advantageous　of　convenient　calculation　by　avoiding　the　cumbering　elastic　stress　categorization　procedure.　In　summary,　the　direct　method　based　on　the　PWC　criterion　is　an　effective　approach　to　solving　the　strength　DBA　problem　of　the　plate-fin　heat　exchanger　header　with　complicated　structure.