Hastelloy Flange Blind

Updated: 2026-07-25

Overview

Hastelloy blind flanges are critical components in piping systems requiring corrosion resistance beyond standard stainless steel capabilities. These forged or machined discs seal pipeline ends during maintenance, testing, or system modifications. Primarily used in aggressive chemical environments, they outperform conventional materials when exposed to hydrochloric acid, sulfuric acid, seawater, and other corrosive media. The blind flange design allows for easy system isolation without permanent pipe modifications.

Structure and Working Principle

Constructed as solid discs with bolt holes matching standard flange dimensions (ANSI/ASME B16.5 or B16.47 specifications), these blind flanges interface with mating flanges using high-strength bolts. When installed, compressive force from bolting creates a metal-to-metal or gasket-assisted seal. The absence of a center hole distinguishes blind flanges from other flange types, enabling complete flow blockage. Special versions may include pressure test ports or lifting lugs for handling convenience.

Key Features

Hastelloy alloys provide unparalleled corrosion resistance, with C-276 resisting both oxidizing and reducing chemicals. B-2 alloy excels in hydrochloric acid service, while C-22 offers broad-spectrum protection. These flanges maintain structural integrity from cryogenic temperatures up to 1,000°F (538°C). Their non-magnetic properties prevent galvanic corrosion when connected to dissimilar metals. Precision machining ensures leak-proof performance even under fluctuating pressure and thermal cycling conditions.

Application Areas

Chemical processing plants utilize these flanges for reactors, distillation columns, and acid storage systems. Petrochemical refineries install them in hydroprocessing units and sour gas pipelines. Pharmaceutical manufacturers specify Hastelloy blind flanges for CIP (clean-in-place) systems. Power generation applications include FGD (flue gas desulfurization) scrubbers and nuclear waste handling. Offshore platforms rely on them for seawater cooling systems and subsea pipeline isolation.

Maintenance and Precautions

Regular inspections should check for crevice corrosion at gasket interfaces and bolt hole fretting. Always use Hastelloy-compatible gasket materials like PTFE or Grafoil to prevent galvanic issues. During installation, follow torque specifications precisely to avoid warping. Never use carbon steel tools on mating surfaces—specialized alloy tools prevent iron contamination. For long-term storage, apply protective coatings and store in low-humidity environments.

B2B Procurement Guide

Specify alloy grade (C-276 being most common), dimensions, pressure class (150# to 2500#), and face type (RF, FF, RTJ). Consider NACE MR0175 compliance for sour service applications. Lead times typically range 4-12 weeks for custom orders. Request mill test reports (MTRs) verifying chemical composition and mechanical properties. For critical services, consider PMI (positive material identification) testing upon receipt. Bulk purchases (10+ units) may qualify for 15-30% discounts.