2021/4/8 · Step 1: Determine Vial Closure Style. Screw Thread Vials. Screw thread vials are typically used for HPLC and LCMS analysis. Screw thread vials do not require additional tools for attaching the cap, nor for removing the cap. Crimp Vials. Crimp Vials are commonly used as a GC Vial for gas chromatography