Last Wednesday afternoon, the utility shop of a food factory in an industrial park called: after the DN50 globe valve downstream of the steam header was fully closed, the pipe section upstream of the steam trap was still hot to the touch, and they suspected internal leakage. The maintenance crew first tightened the gland two turns — no effect; then they suspected the plug sealing surface. When the valve was removed, the flow arrow on the body pointed upstream — the globe valve had been installed backwards. In our years as an authorized SUFA distributor, we've taken more than one call like this. A globe valve installed backwards won't seal tight no matter how far the handwheel turns.

A Globe Valve Installed Backwards Is the Most Common Trap on Steam Lines

A globe valve achieves forced sealing by pressing the disc onto the seat. Conventional straight-through designs require "flow in from below the seat": the media enters under the disc, so the pressure differential helps press the disc firmly onto the seat when closing, and operation takes less effort. Installed backwards, the differential direction reverses and the disc is pushed open a crack, letting high-velocity steam scour the valve's sealing surfaces directly — the longer it runs, the worse the leak.

Before installation, check two things: the flow direction arrow on the body and the orientation of the bonnet. Bending down to check the arrow takes thirty seconds. Reworking an installed-backwards globe valve means cutting pipe, hot work, and a steam shutdown — the whole maintenance window goes up in smoke.

Size and Operating Habits Determine How Long a Globe Valve Lasts

The other half of the problem lies in selection and habits. Some systems use globe valves as control valves, throttling half-open for long periods until high-velocity media grooves the sealing surfaces — after that, closing tight becomes impossible. A globe valve is designed for full open/full close; throttling belongs to control valves and needle valves.

Don't copy the pipe size blindly, either. On low-flow branch lines, choose one size smaller so the disc seats firmly and the sealing surface contact pressure is sufficient. A common sight on real projects: a DN50 line where DN25 would handle the flow, but the copy-the-pipe globe valve sits at a small opening for years and the sealing surface fails first.

If the handwheel won't turn, don't reach for a cheater bar. A stiff globe valve stem is usually dry packing or fouled threads — clean and lubricate first, and overhaul only if that fails. Forcing it bends the stem and creates a brand-new failure.

Troubleshooting Globe Valve Internal Leakage in This Order

If you actually face internal leakage, first verify the flow arrow, then check whether the stem travel reaches the fully closed position — go through the handwheel stop and travel scale. Only when all that checks out should the valve be opened up to inspect the sealing surfaces. In recent years we've seen this repeatedly — the valve was fine, just backwards or not fully stroked, and a brand-new globe valve was replaced for nothing.

Stock spares in advance. Steam system maintenance windows are short; keep one set of internals — disc, seat — for each specification on hand rather than waiting for parts after the steam is off. If selection is unclear, organize the media, temperature, pressure, and size and send them via the contact us page — discuss conditions before price; for structural differences across the globe valve series, go through the product center first.

A network that handles temperature and pressure with ease, undone by one backwards globe valve — that's a bitter way to fail. Next time valves go in during maintenance, will someone on your crew bend down and check that flow arrow?

Suzhou Akameng Automation Equipment Co., Ltd. · Officially Authorized SUFA Distributor (Authorization No. SFSQ-0036) · Tel 0512-66673578 (WeChat 15851489497)