JP4772734B2 - How to install a pressure reducing orifice in gas piping - Google Patents

How to install a pressure reducing orifice in gas piping

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JP4772734B2
JP4772734B2 JP2007108477A JP2007108477A JP4772734B2 JP 4772734 B2 JP4772734 B2 JP 4772734B2 JP 2007108477 A JP2007108477 A JP 2007108477A JP 2007108477 A JP2007108477 A JP 2007108477A JP 4772734 B2 JP4772734 B2 JP 4772734B2
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orifice
gas pipe
gas
pressure reducing
stopper
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雅浩 田口
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Nippon Steel Corp
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Description

本発明はガス配管内に減圧用オリフィスを設置する方法に関するものである。 The present invention relates to a method for installing a pressure reducing orifice in a gas pipe.

製造業などにおける副生ガス、空気、窒素、二酸化炭素等のガスを流通するガス配管設備は、設置より数十年以上経過した設備もあるため、経年劣化対策である補修の実施や他配管との繋ぎ込み工事など操業条件変化に対応した改造を実施している。
高圧状態のガスを流通している配管を対象に、例えば他配管との繋ぎ込み工事を実施する場合、施工利便性の向上や工事中の安全性を高めるために、工事対象範囲の配管内ガス圧力を予め低減させることを目的として減圧用オリフィスを設置する場合がある。
この減圧用オリフィスのガス配管内への設置方法としては、例えば、特許文献１に記載のように、減圧用オリフィスを装入するための開口部をガス配管に設けるものがあるが、この開口部の長手方向は該ガス配管の径方向に設けるものである。更に、ガス配管敷設時に、予め減圧用オリフィス脱着装置を取付けておき、実際に前記減圧を行う際に、ガス配管の上下または左右方向に減圧用オリフィスを動作させ装着するものであった。 Gas piping equipment that distributes by-product gas, air, nitrogen, carbon dioxide, etc. in the manufacturing industry, etc., has been installed for several decades. Remodeling in response to changes in operating conditions, such as connecting work.
For pipes that circulate high-pressure gas, for example, when connecting to other pipes, in order to improve construction convenience and safety during construction, gas in the pipes in the construction target area A pressure reducing orifice may be provided for the purpose of reducing the pressure in advance.
As a method for installing the decompression orifice in the gas pipe, for example, as described in Patent Document 1, there is a method in which an opening for inserting the decompression orifice is provided in the gas pipe. Is provided in the radial direction of the gas pipe. Furthermore, when the gas pipe is laid, a pressure reducing orifice desorbing device is attached in advance, and when the pressure is actually reduced, the pressure reducing orifice is operated and attached in the vertical and horizontal directions of the gas pipe.

実開昭５５−１４５２３９号公報Japanese Utility Model Publication No. 55-145239

しかし、特許文献１によると、減圧用オリフィスは配管内ガス雰囲気内に常に設置された状態にあるため、ガスダストによる駆動部の固着や腐食性ガスによる形状変化が発生する可能性があった。
それを解決するためには、配管敷設後の前記減圧時に任意の既設ガス配管位置へガス配管外部より減圧用オリフィスを設置する必要があるが、既設配管周辺には他ガス配管や電気、計装、または通信ケーブルなど既に多くの支障物が存在していることが多く、ガス配管外部からの減圧用オリフィス設置作業ができず問題となることがある。
また、既設ガス配管を改造して減圧用オリフィス設置装置（例えば、オリフィス本体装入口またはオリフィス固定用治具装入口）を取付ける場合、ガス配管の使用を一時停止する必要があるため、操業ロスによるコストダメージを最小限に抑えられるよう作業時間の最短化に取り組む必要がある。
本発明は、減圧用オリフィスをガス配管内に設置しようとした場合の支障物回避、ガス配管の強度低下の抑制、および、作業性の向上を課題とするものである。 However, according to Patent Document 1, since the decompression orifice is always installed in the gas atmosphere in the pipe, there is a possibility that the drive unit is fixed due to gas dust or the shape is changed due to corrosive gas.
In order to solve this, it is necessary to install a pressure reducing orifice from the outside of the gas pipe to the position of any existing gas pipe at the time of the pressure reduction after the pipe is laid. In many cases, many obstacles such as communication cables already exist, and it is difficult to install the pressure reducing orifice from the outside of the gas pipe.
In addition, when remodeling existing gas piping and installing an orifice installation device for pressure reduction (for example, the orifice body inlet or orifice fixing jig inlet), it is necessary to temporarily stop the use of the gas piping. It is necessary to work to minimize work time so that cost damage can be minimized.
An object of the present invention is to avoid obstacles when a pressure reducing orifice is installed in a gas pipe, to suppress a decrease in strength of the gas pipe, and to improve workability.

本発明は、前記課題を解決するためになされたものであり、その特徴とするところは、ガス配管の上部に、長手方向がガス流れと平行となるようにオリフィス装入用の開口を設け、該オリフィス装入用の開口から前記ガス配管の内径より小さい板状の減圧用オリフィスをガス流れ方向と平行に前記ガス配管内に装入した後、該減圧用オリフィスをガス流れを阻害する方向に回転して固定するガス配管への減圧用オリフィス設置方法である。 The present invention has been made to solve the above-mentioned problems, and the feature thereof is that an opening for introducing an orifice is provided in the upper part of the gas pipe so that the longitudinal direction is parallel to the gas flow, A plate-like pressure reducing orifice smaller than the inner diameter of the gas pipe is inserted into the gas pipe from the orifice charging opening in a direction parallel to the gas flow direction, and then the pressure reducing orifice is set in a direction that inhibits the gas flow. This is a method of installing an orifice for decompression in a gas pipe that is rotated and fixed.

本発明は、ガス配管内に減圧用オリフィスを設置する際、ガス配管の強度低下を抑制することができるので、ガス配管を補強する補強部材のコンパクト化が可能となる。また、ガス配管外部からの作業で減圧用オリフィスを設置できるため、内部足場仮設などガス配管停止中のみ実施可能な作業内容を削減でき、操業ロスによるコストダメージの最小化等の効果を奏するものである。 According to the present invention, when the pressure reducing orifice is installed in the gas pipe, the strength of the gas pipe can be prevented from being reduced. Therefore, the reinforcing member that reinforces the gas pipe can be made compact. In addition, since the orifice for decompression can be installed from the outside of the gas pipe, the work contents that can be performed only when the gas pipe is stopped such as temporary internal scaffolding can be reduced, and the effect of minimizing cost damage due to operation loss is achieved. is there.

本発明者は、ガス配管内に減圧用オリフィス（以下、単にオリフィスとも称す）を設置するのに際し、ガス配管に大掛かりな補強用設備を施すことなく、容易に、かつ早期に前記設置作業を行えるよう様々な検討を行った結果、ガス配管内に減圧用オリフィスを装入するための開口を、該ガス配管の上部（好ましくは頂部）にガス流れ方向に長く、円周方向に短くなるよう設けることで、ガス配管の構造体としての強度低下を抑制でき、該ガス配管の補強用設備をコンパクト化できることを知見した。これは、前記開口をガス配管長手方向に長く設けることが、円周方向に長く設けることに比べガス配管の断面係数を大きくし、ガス配管の屈曲を防止できるからである。ここで、内部ガス圧に対する強度については前記開口をガス配管長手方向に長く持たせる方が2倍弱くなるが、円周方向に補強用リブを溶接するなどの措置により容易に補強可能である。
そして、この開口よりドーナツ形の板状の減圧用オリフィスのガスあたり面をガス流れ方向と平行にして装入した後、該ガスあたり面がガス流れ方向に向くように該減圧用オリフィスを回転して固定することが、設置作業を容易にし、かつ、短時間に実施できるとの知見を得た。
以下に、本発明の一実施の形態に係るガス配管への減圧用オリフィス設置方法を図１〜図３を参照しながら説明する。 The present inventor can easily and quickly perform the installation work without installing a large-scale reinforcement facility in the gas pipe when installing the pressure reducing orifice (hereinafter also simply referred to as an orifice) in the gas pipe. As a result of various investigations, an opening for inserting a pressure reducing orifice into the gas pipe is provided in the upper part (preferably the top) of the gas pipe so as to be longer in the gas flow direction and shorter in the circumferential direction. Thus, it has been found that the strength reduction of the gas pipe structure can be suppressed, and the reinforcement equipment for the gas pipe can be made compact. This is because providing the opening long in the longitudinal direction of the gas pipe increases the sectional modulus of the gas pipe and prevents bending of the gas pipe as compared to providing the opening in the circumferential direction. Here, the strength against the internal gas pressure is reduced by a factor of 2 when the opening is long in the longitudinal direction of the gas pipe, but it can be easily reinforced by measures such as welding a reinforcing rib in the circumferential direction.
Then, after inserting the gas permeation surface of the donut-shaped plate-shaped decompression orifice parallel to the gas flow direction from this opening, the decompression orifice is rotated so that the gas perimeter surface faces the gas flow direction. It has been found that fixing can be carried out easily and in a short time.
Hereinafter, a method for installing a pressure reducing orifice in a gas pipe according to an embodiment of the present invention will be described with reference to FIGS.

（事前準備作業）
ガス配管８に、減圧用オリフィス７を装入するための開口であるオリフィス装入口４、およびオリフィス７の回転防止用のストッパー６を装入するためのストッパー装入口５を設置する手順について図１を参照して説明する。
先ず、長手方向を減圧用オリフィス７の直径より若干長くなるよう長方形に加工した開口部閉止用フランジ１を、長手方向がガス流れ方向と平行となるようにガス配管８の上部に溶接取付けを行う。
また、ストッパー６が装入可能な寸法に加工した減圧用オリフィス固定用ストッパー装入フランジ２を、ガス配管８の両側（ガス配管８の頂部より９０度の位置が望ましい）に溶接取付けを行う。
次に、ガス配管８の曲率に一致するよう加工したガス配管８の補強部材であるリブ３をガス配管８の外側の円周方向へ溶接取付けを行う。このリブ３の取付け範囲はオリフィス挿入口４より長くする。
更に、減圧用オリフィス７を設置しようとするガス配管８の内部ガスを窒素置換する。
そして、開口部閉止用フランジ１およびストッパー装入フランジ２の内側のガス配管鋼材部をジグソー等の切断機で切欠いてオリフィス装入口４および回転防止用ストッパー装入口５を設ける。 (Preparation work)
FIG. 1 shows a procedure for installing an orifice charging inlet 4 that is an opening for inserting a pressure reducing orifice 7 and a stopper charging inlet 5 for charging a stopper 6 for preventing rotation of the orifice 7 into the gas pipe 8. Will be described with reference to FIG.
First, the opening closing flange 1 whose longitudinal direction is made to be a little longer than the diameter of the decompression orifice 7 is welded to the upper portion of the gas pipe 8 so that the longitudinal direction is parallel to the gas flow direction. .
Further, the decompression orifice fixing stopper charging flange 2 processed to a size capable of inserting the stopper 6 is welded to both sides of the gas pipe 8 (preferably at a position of 90 degrees from the top of the gas pipe 8).
Next, the rib 3 which is a reinforcing member of the gas pipe 8 processed so as to coincide with the curvature of the gas pipe 8 is welded and attached in the circumferential direction outside the gas pipe 8. The mounting range of the rib 3 is longer than that of the orifice insertion port 4.
Further, the internal gas of the gas pipe 8 where the decompression orifice 7 is to be installed is replaced with nitrogen.
Then, the gas pipe steel material inside the opening closing flange 1 and the stopper charging flange 2 is cut out by a cutting machine such as a jigsaw to provide an orifice inlet 4 and a rotation preventing stopper inlet 5.

（減圧用オリフィス７装入作業）
次に、オリフィス装入口４より、ドーナツ状（中央に円孔が設けられた円板状）のオリフィス７（外径がガス配管８の内径より１％程度小さい）を装入する手順を図３を参照して説明する。
予め製作した減圧用オリフィス７をクレーン（図示せず）で吊り上げて、オリフィス７をその径方向がガス配管８の長手方向に向いた（即ち、ガス流れ方向と平行な）状態で、オリフィス装入口４よりガス配管８の内部に装入する。
そして、内部ガス流れと正対するように（減圧用オリフィス７の径方向がガス配管８の径方向と一致する、即ちガス流れを阻害する方向に）回転させた状態で、ガス配管８の両側に設けたストッパー装入口５よりストッパー６を装入する。この際、図２に示すように、ストッパー６の対向する一対の足部材６ｂと足部材６ｂの基部間に設けられた足部材６ａとで形成する空間部６ｃ内にオリフィス７の側部が装入する様にストッパー６をセットして、ストッパー６をストッパー装入口５に設けたフランジ２にボルト止めすることによりガス配管８内部でのオリフィス７の回転を防止するが、ストッパー６は流体内圧および流速に基づく動圧に対して許容する強度を有した設計を行う必要がある。
そして、ガス配管８上部の開口部閉止用フランジ１に蓋(図示せず)をして、ボルト止めした後、ガス配管８内にガス導入を行う。
なお、ストッパー６の足部材６ａと６ｂの空間部６ｃはオリフィス７の板厚より５〜７ｍｍ程度広くすることが好ましい。
また、減圧用オリフィス７の中央の円孔の開口面積は、減圧用オリフィス７の上流側および下流側に位置する供給先（工場や配管と直結した設備等）の必要圧からオリフィス式を用いて算出することが好ましい。 (Loading work for orifice 7 for pressure reduction)
Next, a procedure for charging a donut-shaped (disc-shaped with a circular hole in the center) orifice 7 (the outer diameter is about 1% smaller than the inner diameter of the gas pipe 8) from the orifice inlet 4 is shown in FIG. Will be described with reference to FIG.
A pre-manufactured decompression orifice 7 is lifted by a crane (not shown), and the orifice 7 is placed with the orifice 7 oriented in the longitudinal direction of the gas pipe 8 (that is, parallel to the gas flow direction). 4 is inserted into the gas pipe 8.
Then, on both sides of the gas pipe 8 in a state of being rotated so as to face the internal gas flow (in a direction in which the radial direction of the pressure reducing orifice 7 coincides with the radial direction of the gas pipe 8, that is, in the direction of inhibiting the gas flow). The stopper 6 is inserted from the provided stopper charging inlet 5. At this time, as shown in FIG. 2, the side portion of the orifice 7 is mounted in a space portion 6c formed by a pair of foot members 6b opposed to the stopper 6 and a foot member 6a provided between the base portions of the foot members 6b. The stopper 6 is set so as to be inserted, and the stopper 6 is bolted to the flange 2 provided at the stopper inlet 5 to prevent the rotation of the orifice 7 inside the gas pipe 8. It is necessary to design with a strength that allows for dynamic pressure based on flow velocity.
Then, a lid (not shown) is attached to the opening closing flange 1 at the top of the gas pipe 8 and bolted, and then gas is introduced into the gas pipe 8.
The space 6c between the foot members 6a and 6b of the stopper 6 is preferably wider than the plate thickness of the orifice 7 by about 5 to 7 mm.
In addition, the opening area of the circular hole in the center of the pressure reducing orifice 7 is determined by using the orifice type based on the required pressure of the supply destination (such as equipment directly connected to the factory or piping) located upstream and downstream of the pressure reducing orifice 7. It is preferable to calculate.

なお、本発明者は、減圧用オリフィス７の外径とガス配管８の内径との差がガス配管８の内径の約１％である場合、減圧用オリフィス７の開口面積を、減圧用オリフィス７がガス配管８内で回転するために設けた隙間面積分差し引く（置き換える）ことにより、目標とした減圧量が確保できることを確認している。
本実施の形態の減圧用オリフィス７の形状はドーナツ状１枚物としたが、これに限るものではなく、別形状オリフィス（長方形状や十字形状の減圧用板、また分割装入できる形状）を用いてもよい。また、ガス配管の内径より０．５〜２％の範囲で減圧用オリフィスの外径を小さくすることができる。 In addition, when the difference between the outer diameter of the pressure reducing orifice 7 and the inner diameter of the gas pipe 8 is about 1% of the inner diameter of the gas pipe 8, the inventor determines the opening area of the pressure reducing orifice 7 as the pressure reducing orifice 7. It is confirmed that the target pressure reduction amount can be secured by subtracting (replacement) the gap area provided for rotating in the gas pipe 8.
Although the shape of the decompression orifice 7 of the present embodiment is a donut-shaped single piece, it is not limited to this, and another shape orifice (rectangular or cross-shaped decompression plate, or a shape that can be divided and inserted) is used. It may be used. Further, the outer diameter of the decompression orifice can be reduced within a range of 0.5 to 2% from the inner diameter of the gas pipe.

本発明の一実施の形態に係るガス配管への減圧用オリフィス設置方法を示す簡略斜視図である。It is a simplified perspective view which shows the orifice installation method for pressure reduction to the gas piping which concerns on one embodiment of this invention. 同減圧用オリフィス設置方法に使用される回転防止用ストッパーを示す簡略斜視図である。It is a simple perspective view which shows the stopper for rotation prevention used for the orifice installation method for pressure reduction. 同減圧用オリフィス設置方法の減圧用オリフィス装入状況を示す簡略図である。It is a simplification figure which shows the orifice installation condition for pressure reduction of the orifice installation method for pressure reduction.

符号の説明Explanation of symbols

１：開口部閉止用フランジ、２：ストッパー装入フランジ、３：リブ、４：オリフィス装入口、５：ストッパー装入口、６：ストッパー、６ａ、６ｂ：足部材、６ｃ：空間部、７：減圧用オリフィス、８：ガス配管 1: opening closing flange, 2: stopper insertion flange, 3: rib, 4: orifice inlet, 5: stopper inlet, 6: stopper, 6a, 6b: foot member, 6c: space, 7: pressure reduction Orifice, 8: gas piping

Claims (1)

ガス配管の上部に、長手方向がガス流れと平行となるようにオリフィス装入用の開口を設け、該オリフィス装入用の開口から前記ガス配管の内径より小さい板状の減圧用オリフィスをガス流れ方向と平行に前記ガス配管内に装入した後、該減圧用オリフィスをガス流れを阻害する方向に回転して固定することを特徴とするガス配管への減圧用オリフィス設置方法。 An orifice charging opening is provided in the upper part of the gas pipe so that the longitudinal direction thereof is parallel to the gas flow, and the gas flow from the orifice charging opening to a plate-like pressure reducing orifice smaller than the inner diameter of the gas pipe. A method of installing a pressure reducing orifice in a gas pipe, wherein the pressure reducing orifice is rotated and fixed in a direction that inhibits the gas flow after being inserted into the gas pipe in parallel with the direction.
JP2007108477A 2007-04-17 2007-04-17 How to install a pressure reducing orifice in gas piping Active JP4772734B2 (en)

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