RU108656U1 - SAFETY CONTROL STAND FOR REPAIR WORKS AT OBJECTS OF MAIN GAS PIPELINES - Google Patents

Abstract

 Safety control stand during repair work on gas main facilities, consisting of a gas analyzer and pressure gauges, characterized in that it is additionally equipped with a fire alarm with light and sound alarms, gas sensors and two pressure monitoring units, each of which consists of two pressure control manometers , gauge for monitoring overpressure and an electronic pressure sensor with a digital display, which is connected with both temporary-sealing devices and fire alarm with light and sound alarms, which, in turn, is connected to a gas analyzer associated with gas detectors located in the process openings for measuring gas contamination in the pipe.

Description

The utility model relates to regulating and controlling systems, and more particularly to devices for the integrated and continuous monitoring of gas contamination in the pipe and pressure in temporarily sealing devices during repair (fire) work on the underground or above-ground section of the existing main gas pipeline related to hazardous production facilities.

Known automated fire and explosion safety management system, including fire and gas sensors, a computing device, process parameters sensors connected to the corresponding inputs of the computing device, as well as controls electrically connected to the computing device, equipment emergency shutdown subsystems with the formation of a multi-level emergency shutdown system organized by functional and / or territorial-functional basis with the possibility of automatic and remote shutdown by equipment operations (utility model patent №53467, IPC G05B 15/00).

Also known is an automated gas pollution control system (for methane) of air in working areas in hazardous areas (galleries and compartments of superchargers in compressor shops, reduction rooms, switching units and instrumentation and control equipment at gas distribution stations, fuel and starting gas treatment units), including gas detection sensors connected to a computing device, as well as to governing bodies of the emergency exhaust ventilation system (Gazprom standard 2-3.5-454-2010 "Rules for the operation of gas mains odes ").

These stationary automated systems provide:

- process control and emergency shutdown of equipment both automatic and remote;

- control of the main parameters in full only when conducting the technological process (including the control of gas contamination for a hazardous production facility for gas transport only in explosive rooms).

After stopping the process and completely shutting down and releasing equipment and communications from explosive atmospheres, muffling for the production of scheduled or emergency repair (fire) works, the known systems do not provide:

- gas contamination control in the pipe space of equipment and communications;

- monitoring the pressure in temporarily sealing devices installed according to the approved technology through technological openings into the in-pipe space of the repaired section of the pipeline disconnected by shutoff valves from the place of hot work on the linear part of the main gas pipelines.

There is a known regulation on the preparation and conduct of repair (fire) work at hazardous production facilities of the Unified Gas Transportation System of Russia, which establishes methods and methods for shutting off valves on equipment and pipelines, bleeding gas, installing and monitoring overpressure, cutting technological holes with an additional installation in the pipe space temporarily sealing devices, purging, welding and installation work, displacement of the gas-air mixture from the repaired About equipment or pipelines. At the same time, gas contamination in the hazardous area, overpressure in the pipeline, and pressures in temporarily sealing devices are controlled by separate measuring instruments — portable gas analyzers, manometers, drag gauges and direct pressure gauges (standard Gazprom RD - 2005 “Typical Instructions for the Safe Carrying Out of Fire Operations at Gas Objects” Gazprom OJSC, developed by the Scientific Research Institute of Natural Gases and Gas Technologies - VNIIGAZ in accordance with the “Standard Instruction on the organization of the safe conduct of hot work at explosive and explosive and fire hazardous facilities ”, approved by the State Technical Supervision Service of Russia on June 23, 2000)

In accordance with the specified regulations:

- for the entire period of repair (fire) work, they monitor the state of the air environment, including the in-pipe space of the repair section in explosive and working areas with portable gas analyzers;

- designate duty observers for the state of the hazardous area in order to signal the immediate termination of work in the event of a pre-emergency situation or additional danger;

- gas contamination is controlled by portable gas analyzers at least every 30 minutes;

- before cutting technological holes in the gas pipeline, pressure is measured by pressure gauges, which are installed on disconnecting devices (crane units) and at the place of repair (fire) work. Manometers are connected to the gas pipeline using a tube with a special conical nipple, pressed into a hole with a diameter of 6-8 mm, drilled in the upper part of the gas pipeline at the place of repair (fire) work;

- finishing cuts of the gas pipeline and welding and installation work to restore it is performed after installing temporarily sealing devices with gas in the pipe and foundation pit not more than 20% of the lower concentration limit of ignition;

- during repair (fire) work related to the separation of the gas pipeline, rough cuts are made after the localization of the place of work with temporarily sealing devices;

- temporarily sealing devices are installed in the gas pipeline at a distance of at least 8-10 m in both directions from the place of repair (fire) work between the technological holes and the place of work. A temporarily sealing device placed in a gas pipeline is pumped with air or inert gas to the required pressure;

- pressure control inside the temporarily sealing device is carried out by pressure gauges.

However, these parameters, the control of which must be ensured when performing work of increased danger on the gas equipment and gas pipelines taken out for repair, are not automatically controlled and cannot be controlled by the well-known automated fire and explosion safety control systems or automated process control systems.

The process of an emergency in the working area, including due to changes in the in-pipe space, is often instantaneous and the slightest delay in making a decision can lead to an air-gas mixture explosion, an accident and industrial accidents. An important role is played by the method of notifying workers involved in the relevant stages and carrying out hot work, including workers in the foundation pit or trench, at the repair section of the gas pipeline or other equipment of the main gas pipeline facility.

The notification process is complicated by the fact that during the repair (fire) work, increased noise is characteristic due to the working internal combustion engines of power plants, mechanisms, grinders, etc., which makes it difficult to immediately alert and, therefore, immediately evacuate workers from the danger zone.

The technical result achieved by the authors ’proposal is to increase technological safety during the repair (fire) works by continuously monitoring the gas content in the in-pipe space of the repaired section of the main gas pipeline and the working pressure in temporarily sealing devices.

The stated result is achieved by the fact that the safety control stand consists of a gas analyzer, temporarily sealing devices, a fire alarm with light and sound alarms, gas pollution sensors and two pressure control units, each of which consists of two pressure control manometers, an overpressure control manometer and an electronic sensor pressure with a digital display, which in turn is connected with both temporary sealing devices and a fire alarm with light and sound alarm, while it is in turn connected to a gas analyzer connected to gas detectors located in the process openings for measuring gas contamination in the in-pipe space.

The safety control stand in practice consists of the following elements:

- a stationary two-channel gas analyzer with a control unit - 1 pc .;

- remote optical explosion-proof gas pollution sensors - 2 pcs .;

- intrinsically safe clamps for mounting sensors - 2 pcs .;

- fire alarm combined with sound and light (stroboscopic) alarm - 1 pc .;

- shielded connecting cable;

- distribution boxes - 4 pcs.;

- connecting cable;

- two pressure control units, where each unit is technologically connected by impulse tubes, ball valves and includes three pressure control manometers and one electronic pressure sensor with a digital display;

- impulse connecting tubes;

- coupling ball valves - 8 pcs .;

- temporarily sealing devices - 4 pcs., of which 2 pcs. walk-through;

- rubber connecting hoses.

Figure 1 presents a block diagram of a security control stand.

To the control unit of the factory stationary two-channel gas analyzer 1, mobile located outside the working area of hot work, remote explosion-proof gas sensors 3 are connected via individual distribution boxes 2 through cables 3. The power supply of the stationary two-channel gas analyzer 1 is carried out from a single-phase 220 V AC network with a frequency of 50 Hz. The supply voltage to the gas sensors is supplied through an intrinsic safety barrier. Each sensor through a junction box 2 is connected via a standard communication channel to the gas analyzer 1. In the sensors, the analog signals are converted to digital form and fed into standard communication channels.

Remote explosion-proof gas sensors 3 are installed one by one with the help of intrinsically safe clamps in the technological holes of the pipeline being repaired on one or the other side of the place of repair (fire) work. The control unit of the gas analyzer 1, connected with remote explosion-proof gas sensors 3, compares the measured values of the gas concentration with predetermined threshold values, generates control signals for light and sound alarms and sends a signal to the combined firefighter siren 4.

The combined fire alarm 4 is placed at a safe distance in the field of visibility from the site of the hot work. Two pressure monitoring units 5, each of which consists of two pressure monitoring gauges 6, one overpressure pressure gauge 7 and an electronic pressure sensor with a digital display 8. Each pressure monitoring unit 5 is connected to a pair of temporarily sealing devices 9. Technological pressure monitoring gauges 6 connected by rubber hoses 10 with two temporarily sealing devices 9, installed two in each technological hole on one or the other side of the place of repair (fire) work . Pressure gauges for controlling overpressure 7 are technologically connected by rubber hoses 11 through passage-time temporary sealing devices 9 with an in-pipe space for monitoring overpressure in a disconnected section of the gas pipeline between shut-off valves 12 and temporary sealing devices 9 that are external from the place of work.

An electronic pressure sensor with a digital display 8 of the pressure control unit 5 is connected to the siren by a combined firefighter 4. On digital displays 8, threshold pressure values of external temporarily sealing devices are set.

The pressure control units 5 through taps 13 are connected to a portable compressor 14 for pumping or pumping temporarily sealing devices 9 with air.

Stand security control works as follows.

In the stationary gas analyzer 1, threshold values of gas concentration are set and set, for example, when exceeding 0.5% CH ₄ by volume, an alarm signal, if exceeding 1% CH ₄ , an alarm signal. Stationary gas analyzer 1 provides continuous monitoring of gas contamination in the in-pipe space of the shut-off valve disconnected with gas bleeding of the repaired section of the pipeline using remote explosion-proof gas pollution sensors 3 installed in the technological holes of the gas pipeline on each side of the firing site in accordance with the approved repair (firing) production technology works.

The analog signals in the sensors are converted to digital form and received from the outputs of the remote explosion-proof gas sensors 3 through a communication channel to a stationary gas analyzer 1, the control unit of which compares the received data with the set threshold values. When threshold values are exceeded, an alarm is generated with its transmission to the input of the stationary gas analyzer 1. “Light” and “sound” alarms are triggered directly on the control unit of the stationary gas analyzer 1 and on the combined fire warning device 4, which is in the zone of visibility of the performers and those responsible for the work .

Continuous monitoring of the working pressure in temporarily sealing devices 9 installed inside the pipeline through technological holes, as well as monitoring of overpressure in sections of the disconnected gas pipeline between external temporarily sealing devices 9 and shut-off valves 12, which disconnects the workplace 15 from all sides, is carried out by personnel using the unit pressure control 5. On electronic pressure sensors with digital displays 8, threshold pressure values in s are set and programmed correspondence with the passport data of temporarily sealing devices 9. The digital displays 8 display information on the pressure in the external sealing devices 9. If the overpressure deviates in any of the external temporarily sealing devices 9, the electronic pressure sensors 8 generate and transmit a signal to the fire alarm 4, where “Light” and “sound” alarms are triggered.

All of the above signs can provide:

- continuous monitoring of individual parameters (gas contamination in the in-pipe space of the repaired (disconnected) section of the gas pipeline and the magnitude of the working pressure in external temporarily sealing devices when carrying out work of increased danger on the hazardous production facility of the linear part of the main gas pipeline that has been put out for repair (with a process stop, respectively);

- detection and immediate notification of personnel about dangerous changes in the in-pipe space to suspend repair (fire) operations, evacuate workers from the danger zone until the causes of the emergency are identified and eliminated.

Claims (1)

Safety control stand during repair work on the main gas pipeline facilities, consisting of a gas analyzer and pressure gauges, characterized in that it is additionally equipped with a fire alarm with light and sound alarms, gas sensors and two pressure monitoring units, each of which consists of two pressure control manometers , gauge for monitoring overpressure and an electronic pressure sensor with a digital display, which is connected with both temporary-sealing devices and fire alarm with light and sound alarms, which, in turn, is connected to a gas analyzer associated with gas detectors located in technological openings for measuring gas contamination in the pipe.