Hastelloy C276 flanges are made of a nickel-chromium-molybdenum alloy called Hastelloy. The composition includes 50.99% nickel, 14.5% chromium, 15% molybdenum and carbon, manganese, silicon, sulfur, cobalt, iron and phosphorus. Hastelloy C276 flanges have a high melting point of 1370 degrees Celsius.