Bellows Seal Globe Valve Delivery for Chlorine Service — South Africa Chemical Industry

Product Overview

Nortech Engineering Corporation has completed a delivery of extended stem globe valves and bellows seal globe valves for a chlorine gas application, covering sizes from 2″ to 4″ in pressure classes 150# and 300#. Both valve types share a common cast LCB (carbon steel, low-temperature grade) body and bonnet, giving the batch a consistent pressure-temperature rating and simplifying spare parts management for the end user. The extended yoke sleeve keeps the packing gland and handwheel well clear of the pipeline insulation and process piping, which improves access for routine maintenance and reduces the risk of operator exposure when working near a line carrying a hazardous medium such as chlorine gas.

Design and dimensions for the full batch follow ASME B16.34 for pressure-temperature ratings and shell wall thickness, with flanged end connections machined to ASME B16.5 facing and drilling requirements. Straight-pattern globe valve geometry was retained across both the standard bellows seal units and the extended stem units, giving predictable flow characteristics and consistent Cv values for the project’s line sizing calculations. Each valve was assembled with a rising stem, outside screw and yoke (OS&Y) configuration, so stem position is visible at all times — a feature specifically valued by operators working with toxic or corrosive gas lines where valve status must be confirmed at a glance.

Technical Specifications

Seat and disc sealing surfaces are hardfaced with Stellite (STL) cobalt-based hard alloy, applied by weld overlay and precision machined to a fine finish for reliable metal-to-metal shutoff and resistance to wear, galling, and erosion under repeated cycling. This hardfacing configuration is the standard trim baseline that Nortech applies across its globe valve range before any medium-specific material upgrades are considered.

Given the corrosive nature of the process medium, the stem and bellows on this batch were upgraded from the standard trim to C276 (Hastelloy), a nickel-molybdenum-chromium alloy recognized for its resistance to both wet and dry chlorine attack as well as a wide range of oxidizing and reducing chemical environments. Selecting a single alloy for both the stem and the bellows element avoids galvanic mismatch at the weld and mechanical interfaces, which is a common failure point when dissimilar corrosion-resistant alloys are combined in the same wetted assembly.

The bellows seal itself functions as a secondary zero-leakage barrier around the stem, replacing reliance on packing alone to contain the process medium. Multi-ply, hydroformed bellows construction was used to give the assembly the flexibility needed for repeated open-close cycling without fatigue cracking, while a back-up packing set below the bellows provides an additional containment layer in the unlikely event of bellows failure. This redundant sealing arrangement is the primary reason bellows seal globe valves are specified for chlorine, ammonia, and other toxic or environmentally regulated gas services, where fugitive emissions at the stem are not an acceptable risk.

Packing selection and gland assembly were specified to meet the TA-Luft low-emission standard, the German technical guideline widely referenced internationally for fugitive emission control on valve stems. Meeting TA-Luft requirements involves a defined packing set, controlled gland loading, and — where applicable — leak-rate verification, and it is frequently requested by end users even on bellows seal valves as a second layer of assurance. As a corrosion resistant valve manufacturer, Nortech configures body, trim, sealing, and packing materials independently for each project so the final specification matches the chemical compatibility profile of the actual process medium rather than a generic catalog default.

Application & Delivery

This shipment was supplied to an end user in South Africa’s chemical processing sector, where chlorine gas handling demands both mechanical reliability and strict leak containment. Chlorine is handled across a range of industrial applications in the region, including water treatment disinfection, pulp bleaching, and general chemical manufacturing, and in each case valve integrity at the stem is treated as a critical safety parameter rather than a purely operational one.

As a china bellows seal globe valve supplier, Nortech has shipped multiple batches of this configuration to the same region over several years, and the valves’ performance in continuous chlorine service has been confirmed through repeated field use rather than laboratory testing alone. This ongoing relationship has allowed the trim specification — Stellite-faced seat and disc paired with C276 stem and bellows — to be refined and standardized for the customer’s specific process conditions, reducing the need for re-engineering on repeat orders.

Each unit in this delivery was factory tested for shell and seat tightness in line with API 598 acceptance criteria, with mill material certificates, hydrostatic test reports, and dimensional inspection records issued and reviewed prior to shipment. Valves were painted, tagged, and flange-protected for sea freight, with documentation packaged to support customs clearance and site incoming inspection on arrival in South Africa.

Nortech continues to support long-term chlorine and chemical service valve programs with consistent trim configuration, complete material traceability, and repeatable documentation across repeat orders, giving process engineers a dependable source for corrosion-resistant globe valves as expansion or replacement needs arise.