Description

What Is a Scraper Passage Indicator?

A scraper passage indicator detects and confirms when a pipeline cleaning pig passes a fixed point. Operators install it at launchers, receivers, or intermediate stations along the line. The device extends a plunger into the bore and physically contacts the pig.

This contact raises a visible flag and, on electrical models, closes a dry-contact switch. As a result, you get certain proof of passage instead of pressure guesses.

Key Specifications

Parameter	Specification
Connection Types	2″ Flange (ASME B16.5); Flange 20 mm adjustable; 2″ welded NPT; 2″ welded adjustable
Pipe Size	From 2″ (DN50) upward
Design Pressure	ANSI 150# to 2500# (flange); up to 10,000 Psi (69 MPa, boss)
Operating Temperature	−20°C to +120°C (special seals on request)
Trigger Type	Bi-directional / Bi-directional feather / Uni-directional
Indicator Type	Manual-reset flag; flag + electrical; digital display + electrical
Insert Depth	21 mm (bi-directional) / 13 mm (uni-directional)
Body Material	PTFE-coated A105N / 304SS / 316SS / Duplex (F51) / Inconel
Internal Parts	316SS / Duplex / Inconel 625
Ingress Protection	IP65 / IP66
Explosion-Proof	ExdⅡ BT4
Corrosion Standard	NACE MR0175 / ISO 15156
Output	DPDT / SPDT, DC24V 3A–5A; M20×1.5(F) or 1/2″ NPT(F)
Remove Under Pressure	Yes (removable types) / No (standard types)
Certifications	ASME U-Stamp quality, ISO 9001, CCC, Exd

How Does a Scraper Passage Indicator Work?

The trigger mechanism extends into the pipeline through a 2-inch connection. When a pig touches the plunger, the mechanism pivots. A magnetic coupling then transfers the motion through a sealed barrier to the indicator head. The flag rises to a clear, visible position.

For electrical models, a dry-contact SPDT or DPDT switch closes at the same time. Therefore, your SCADA or DCS system receives a remote signal without any fluid crossing the seal.

Resetting is manual. The operator must lower the flag after confirming the passage. This deliberate step prevents accidental resets and keeps the operational record clean.

Why Choose Our Scraper Passage Indicator?

• Magnetic anti-leak seal— A magnetic coupling isolates the head from pipeline fluid. No dynamic seal wears or leaks over time.
• False-signal immunity— The plunger responds only to solid pig contact, not flow, surges, or turbulence.
• Online retrievability— Removable models pair with a pressure removal tool for live-line service without shutdown.
• NACE MR0175 compliance— All wetted parts use 316SS, duplex, or Inconel for sour (H2S) service.
• Exd explosion-proof— Heavy-duty enclosure rated ExdⅡ BT4 sends dry-contact signals to your panel.
• Hydro-tested— Every unit passes a 1.5× design-pressure test before shipment, with full traceability.

Pair it with our pipeline pig launchers and receivers for a complete pigging station.

Application Scenarios

Use it on crude, gas, water, and chemical pipelines during pigging campaigns. It confirms pig launch, intermediate passage, and final receipt. Additionally, it tracks progress on long cross-country lines and offshore tiebacks.

For instance, place one at every intermediate valve station. Specifically, this gives step-by-step confirmation instead of one uncertain endpoint signal.

Frequently Asked Questions

What is a scraper passage indicator used for?

It confirms that a cleaning pig has passed a point in the pipeline. Operators use the flag or electrical signal to verify launch, track progress, and detect a stalled pig before damage occurs.

Can I install a scraper passage indicator on a live pipeline?

Yes. Flanged and welded-adjustable models allow hot-tap installation on pressurized lines. A paired removal tool lets crews withdraw the sensing unit without depressurizing the pipeline.

Does the indicator work with any pig?

It detects foam, polyurethane, metal-bodied, sphere, and intelligent (ILI) pigs. A bi-directional feather trigger gives extra sensitivity for soft foam pigs and heavy-wax crude.

Is the scraper passage indicator suitable for hazardous areas?

Yes. The enclosure is ExdⅡ BT4 explosion-proof and IP66 protected. NACE MR0175 wetted parts are available for H2S sour service.

How do I send the signal to my control room?

Electrical models provide a dry DPDT or SPDT contact at DC24V 3A–5A. You wire it directly to your SCADA or DCS system for remote alarm and logging.