Pig Indicator

Pig indicator is a new product used to determine whether the pig in the pipeline passes through the installation point when the ball-through pipeline pigging.


Definition of the pig indicator

Pig indicator: The pig indicator is a general term for special equipment used in ball-through pipelines and installed at the front end of the receiver, the ball barrel, or at a point in the pipeline to indicate whether the pig passes through the point in the pipeline.

A pig indicator is a new product used to determine whether the pig in the pipeline passes through the installation point when the ball-through pipeline pigging. This product has been used in the country’s major oil fields, petrochemical industry, tap water, city gas, mines, ships, power plants, and other departments.

pig indicator (2)


SN3I-TQZ (SN2-TQZ-B) flag pass ball indicator is a mechanically triggered pass ball indicator for monitoring pig passage. When the pig passes, the flag changes from horizontal to upright. The ball indicator is installed with a 2 “flange, and the parts in contact with the medium, including the flange sealing surface (or flange), according to user needs can be made of carbon steel, stainless steel (such as 316; 316L) manufacture.

Note: SN2 — TQZ-B and SN3 ITQZ are the same instrument. After two mounting modes and four displays are developed, SN2 is used to represent the flange (including pressure disassembly) mode, and SN3 is used to represent the base mode; A, B, C, and D respectively represent four kinds of displays: pop-up flag display, corner flag display, corner flag display + remote transmission, date/time display + remote transmission/manual + automatic reset.

Working principle

The firing pin that can be triggered bi-directionally is installed at the end of the extension sleeve and is probed into the inner part of the pipe near the pipe wall through the 2 “nozzle. When the pig passes through, the firing pin is moved to pull the connecting rod in the seal sleeve, indicating that the flag shaft rotates 90° under the action of the torsion spring, from the horizontal state to the upright state. The flag can be reset by flipping it clockwise.

Main technical indicators:

Main body working pressure: 0-15MPa(can design 0-26MPa)

Standard: 2″ ANSI 600# RF flange

300# 900# RF flange (or 1500# flange) can be configured according to the user’s needs.

Operating temperature: -20-100℃

Thrust length (the length from below the flange to the end of the extension sleeve — the distance from the top of the flange to the inner wall of the pipe): 150mm; Custom made

Parameters of remote transmission outlet type:

Interface: 1/2NPT;

Switch type: SPDT or DPDT Switch Capacity: 3A/24VDC

pig indicator


Dielectric compatibility

SN3I — TQZ is petroleum grade

Applicable medium: compressed air, cold water, seawater, oil, natural gas, aliphatic hydrocarbon oil.

Sealing materials are not suitable for media: strong oxidizing media, chlorinated hydrocarbons, aromatic hydrocarbons, alkaline hydrocarbons, ketones, and esters.


SN3I — TQZ (H) is a chemical grade

Sealing material to compressed air, water vapor, superhot water, cold water, seawater, aromatic/fatty oil, acid, base, alcohol, aldehyde, amine, ether, ester, and ketone excellent corrosion resistance.

Sealing material to strong oxidants, ethylene oxide, and propylene oxide corrosion resistance is very good.

The sealing material is not suitable for media: > High-temperature amine at 70℃

Installation method

1. Flanges (flange specification, grade, mounting hole distribution, etc., shall be in accordance with ANSI 16.5 or Custom standards) shall be pre-installed on the pipe prior to installation of the ball-through indicator. Distance from flange top to pipe wall is 150mm or according to custom size.

2. Remove the display with the threaded nozzle from the flange base as shown below.


3. Use the gasket suitable for the flange used (the thickness of the gasket is 3-5mm when RF flange is used), The gasket is between the two flanges, and the action direction of the firing pin of the indicator is to the direction of the pipeline (that is, the notch is to the direction of the pipeline). Insert the extension sleeve into the pipe and bolt the flange base to the pipe joint.

4. At the thread of the display thread nozzle, wrap several layers of raw material belt and turn the thread until the limit position is reached. The docin.com tube is mounted on the flange base threaded interface. The depth of the screw nozzle is limited, screwiest the display

After the preceding steps are complete if you want to adjust the direction of the monitor, loosen the four nuts slightly from the method of the monitor, turn the watch head clockwise, and tighten the loosened nuts when they reach the proper position.


The above part of the flange of the instrument can be disassembled with pressure, but the mechanical parts in this part are not easy to damage, it is recommended that the user do not disassemble.

The following part of the flange for sealing type ○ ring is a wearing part, overpressure will reduce the service life, such as leakage, it is recommended to return to the manufacturer for maintenance and replacement.



pig indicator




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