SIGMA GROUP: FABRICATION, MACHINING, POST-WELD HEAT TREATMENT, GRIT BLASTING, PAINTING ETC. SERVICE CENTER FOR MECHANICAL SEALS. MECHANICAL SEALS FOR ROTARY EQUIPMENTS. COMPRESSORS & BLOWERS. BALL, GATE, GLOBE, CHECK, BUTTERFLY, SAFETY RELIEF AND CONTROL VALVES. GAS ANALYSERS. SAFETY ITEMS. HEAT TREATMENT & STRESS RELIEVING