西部管道密封培训

西部管道密封培训

JohnCrane Tech(Tianjin) Co.,Ltd

培训内容概述

密封基础知识密封系统知识密封的安装要求密封的失效大致判断与客户技术人员进行交流

机械密封基础第一部分

Concepts of Mechanical Seals机械密封概念

Shaft

Process Fluid密封流体

Leakage泄漏

Environment环境

Vessel Wall釜壁

The Basic Sealing Problem:Preventing Leakage基本的密封问题 : 防止泄漏

Shaft

Process Fluid流体流动

Leakage泄漏

Environment环境

Vessel Wall釜壁

The Concept of anEnd Face Mechanical Seal机械密封端面的概念

Shaft Movement

轴的运动

Required Features 必须的特征 Small axial clearance 小的轴向间隙 Self adjusting 自调节

Mating Ring配合环

Primary Ring补偿环

Secondary Sealing Element辅助密封

A Flexible Seal Flexible 机械密封 Hydrostatic loading 流体静力学负荷 Secondary sealing elements 辅助密封 Replaceable parts 可替换的部件

O-Ring O 型圈

Shaft 轴


Primary Ring 补偿环Snap Ring 卡环

Anti-X Ring 挡环O-Ring O 型圈

Disk 推环Springs 弹簧Retainer 传动套

Set Screw 定位螺丝

An Example of a Complete Seal

Simply put, a mechanical seal is:简单的说 , 机械密封就是 :

1. A wearable, stationary, primary sealing element

一个耐磨 , 静止的密封件

2. A wearable, rotating, primary sealing element

一个耐磨 , 旋转的密封件

3. A secondary sealing element

二次密封

4. A mechanical loading device to press primary sealing elements 1 and 2 against one another, and

使件 1 和件 2 相互贴合的机械装置

5. Auxiliary components to complete seal

辅助密封

Non-flashing没有闪蒸

Flashing闪蒸

Parallel平行

Converging收敛

Diverging发散

Face Separation密封面分离

Shape:形态

Gap:间隙

Fluid:流体

The Sealing Interface 密封接触面

Lubricant 润滑剂Separation分离面

Magnified Surface A 放大面

Magnified Surface B 放大面

Heat 热量

The Sealing Interface 密封面 Lubrication Purpose: 润滑目的

Separate surfaces 分离两个面 Prevent contact of high surface points 防止出现面接触 Reduce friction/heat generation 减少摩擦 / 生热

Process Fluid Acts as Lubricant Between Faces 流体在两个面之间充当润滑剂的过程

Gland 密封端盖Pump Housing

泵腔

Process Fluid工艺流体

Invisible Leakage: 不可见泄漏Fluid Evaporates Upon Reaching Atmosphere微量的泄漏在大气侧蒸发



Gland 密封端盖

Pump Housing泵腔

No Fluid Or Dry Running没有流体或者干运转



Without Lubrication, Faces Run Dry And Overheat 没有润滑干运转导致过热


Primary Ring 补偿环

Heat Generation 生热 Rubbing 摩擦 Viscous Shear 粘性剪切力

Heat Transfer 热传递 Conduction 传导 Convection 对流

Injection 注入

Flushing 冷冲洗 Removes Heat 带走热量 Replenishes Cool Clean Lubricating Liquid

补充润滑液

Primary Seal: Flush 基本密封 : 冲洗Single Seal Flushing By - Pass from Discharge (API Plan 11)单密封通过出口进行冲洗

By- pass Line fromPump Discharge to Seal Gland 从泵出口到密封端盖的管线

Discharge 出口

Flow流动

Suction入口

Primary Seal: Flush 基本密封 : 冲洗

Minimum Pressure.3 bar / 5 psi

Above A?最小压力值要大于 A

处 0.3Bar

Flow流动

Discharge出口

Suction入口

Restrictional Device(Bushing) 限流装置

Single Seal Flushing from External Source (API Plan 32)单密封通过外部来源进行冲洗

A

Primary Seal: Quench 基本密封 : 急冷

Restrictional Device (Packing)限流装置 ( 盘根 )

Quench Source 急冷源

Process Fluid 工艺流体

Single Seal Quench from External Source (API Plan 62)单密封通过外部急冷

API Piping PlansAPI 冲洗方案

第二部分

JOHNCRANE

API Piping Plans API 冲洗方案

Integral (internal) recirculationfrom pump discharge to seal

内部循环从泵的出口到密封

Advantage Advantage 优点优点 - No external piping 没有外部冲洗 Limitations Limitations 局限性局限性 - Changing flow rate required dismantling of pump 改变流量需要拆泵 - For clean pumpages only 只能是适用干净的介质


Points to Note for API Plan 02: API 02 冲洗方案应注意的事项：

-The injection tapping is used for venting prior to start–up. - 在开车前，入口用来进行放空

-API plan 02 is often used together with plan 62, especially on high temperature bellows seals. 冲洗方案2 经常与 62 一起用，特别是用在高温波纹管密封


No flushing to the mechanical seal (‘dead-ended’)机械密封里没有冲洗

Points to Note for API Plan 11: API 冲洗方案 11 应注意的事项

- Use an orifice to restrict the flow rate if the discharge pressure is 3 bar higher than seal chamber pressure. 如果出口压力高于密封腔压力 3bar ，需要用一个孔限制流量

- Use on clean and low abrasives duties 用在干净，含磨石性颗粒少的工矿


Seal Flushing By-Pass from Discharge单密封通过出口进行冲洗

Recirculation from seal chamber through a flow control orifice and back to pump suction 从密封

腔里出通过一个孔板返回到泵的入口

Points to Note for API Plan 13:API 冲洗方案 13 应注意的事项- Use an orifice to restrict the flow rate if the seal chamber pressure is 3 bar higher than suction pressure. 如果密封腔压力高于入口压力 3bar ，需要用一个孔板限制流量

- handle abrasives duty better than API plan 11处理含有磨石性颗粒的工矿 13 方案号优于 11 方案

- higher seal chamber pressure to suppress vaporisation 较高的密封腔压力可抑制它的汽化


+ =Points to Note for API Plan 14: API 冲洗方案 14 应注意的事项：

- Flow back to suction side will evacuate vapours that may collect in seal chamber.

- Recommended for light hydrocarbon service.


Recirculation from pump discharge through a flow control orifice and cooler to seal

Open Loop Cooling CircuitOpen Loop Cooling Circuit

Cooling Water

Outlet 冷水出口

Cooling Water

Inlet 冷水入口


Recirculation from a pumping ring in the seal chamber through cooler and back to seal Closed Loop Cooling Circuit Closed Loop Cooling Circuit 冲洗液通过密

封腔中的泵效环从密封腔中流出经过换热器，再返回到密封中，形成自封闭循环。形成封闭的冷却回路形成封闭的冷却回路

Throat bushing

Suction入口

Discharge出口

18 - 24"

Vent at highest point of

the piping 排气在管线的最高点

Cooling Water Outlet冷水出

口

Cooling Water Inlet 冷水入口

mechanical seal with pumping ring

Heat exchanger换热器


Points to note for API Plan 23:

Thermosyphon design 热虹吸设计 * heat exchanger 换热器

18 to 24“ above pump centre line. 在泵中心线以上 18 to 24"

* Prevent overheating in standby and start–up. * 在泵启动和备用时，要防止过热。

Install close fitting neck bushing at the bottom of seal chamber to isolate the heat from the impeller end. 在密封腔底部安装喉部衬套用来隔离从叶轮传出的热量

Used on high temperature applications to minimise heat load on the cooler by cooling only small amount of liquid that is recirculated. 用于高温工况，通过冷却密封腔的小部分的循环流体来使冷却器的热负荷降至最低 .

For high temperature boiler feed pump applications 用于高温锅炉给水泵上

Other applications 其他应用

* high temperature liquid close to bubble point. * 接近沸点的高温液体 .


Recirculation from pump discharge through a cyclone separator delivering clean fluid to the seal and fluid with solids back to pump suction line 冲洗液从泵出口流出，通过一旋液分离器，使干净流体进入

密封腔，带有颗粒的流体返回到泵入口处形成封闭循环

Clean overflow

Underflow

Inlet


Points to Note for API Plan 32:对于 API plan 32 须注意 :

- Chose a proper source of seal flush to eliminate the potential for vaporisation of the injected fluid and to avoid contamination of the fluid being pumped with the injected flush. 选择合适的密封冲洗源，以减少冲洗流体的汽化，同时可避免冲洗流体被污染。

- Install a labyrinth bushing at the bottom of the stuffing box to control the flushing and pressure if necessary.

- - 如有必要的话，在密封腔底部安装喉部衬套或迷宫密封来控制冲洗和压力。


Single Seal Flushing from External Source单密封通过外部来源进行冲洗

Throat Bushing

Recirculation from pump discharge through a cyclone separator delivering clean fluid through a cooler and then to

seal and fluid with solids back to pump suction line

Cooling Water Outlet

Cooling Water Inlet


Needle valve

External reservoir providing a dead-ended blanket of fluid to the quench connection of the gland.

Points to Note for API Plan 51: 对于 API plan 51 须注意 :

-- Dead ended blanket on atmospheric side of seal to prevent freezing of moisture. Seal face will not stick together when the pump started. - 在密封大气侧，一端封闭的情况可防止潮气的冻结，这样在泵启动时，密封面就不会粘接在一起。 Typical application : Typical application : 典型的应用典型的应用Pump operating below 0° C 应用于泵在 0°C 以下

-- API 610 8th Edition has eliminated this piping plan.API 610 第八版已经取消这个冲洗方案

--



A fluid used as a lubricant or buffer between dual mechanical seals. 这种液体象缓冲剂，润滑剂用在双机械密封 The buffer fluid is always at a pressure lower than the pump process pressure being sealed.缓冲液的压力通常低于被密封的介质的压力

A fluid which is introduced between dual mechanical seals to completely isolate the pump process liquid from the environment.双机械密封里的隔离液用于是泵的工艺液体与大气分离 Pressure of the barrier fluid is always higher than the pump process pressure being sealed.隔离液压力总是高于泵的运作压力

The purpose of fluid circulationis to remove heat from mechanical seal


Pumping ring

Pump

On applications below ambient temperature, circulation of barrier fluid may not be desirable. 这种情况适用于比室温低的工况，隔离液的循环不能满足要求。 The atmosphere will heat the reservoir and consequently add heat to the seal area. 外部对储罐进行加热，从而，对密封区域进行加热。

T2

T1

Fluid circulation by temperature difference between the seal and reservoir. 流体依靠密封腔和储罐的温差进行循环 Higher temperature liquid at seal has lower density rises to the reservoir. 密封中的高温流体密度较小，依靠热虹吸现象上升到储罐中

Lower temperature liquid at reservoir has higher density falls to the seal to provide cooling.储罐中的低温流体密度较大，下降到密封腔中对密封进行冷却


Points to Note for API Plan 52:

Typically used with an Arrangement 2 unpressurised dual seal. 通常用于不带压双封

During normal operation, circulation is maintained by an internal pumping ring. 在正常操作情况下，通过腔内的泵效环维持循环

The reservoir is usually continuously vented to a vapour recovery system and is maintained at a pressure less than the pressure in the seal chamber.储罐通常与回收系统相连通，罐内压力通常低于密封腔压力

Pressure Gauge 压力计

Level Gauge 水准仪Fill valveOrifice

Drain

Level Switch (H) 电平开关Level Switch (L)

Pressure Switch 压力开关(Normally Open)

Vent valve 排气阀

External reservoir providing buffer fluid for the outer seal of an unpressurised dual seal arrangement.外部储罐对不带压双封的外密封起缓冲液的作用


Pressure Gauge 压力表

Level Gauge 水准仪Level Switch (L)电平开关

Vent Valve 排气阀(Normally Close) 通常关着

Orifice

Pressure Switch 压力操纵开关 External Pressure 外部压力 Source

One-way Block Valve(Normally Open)


Typically used with an Arrangement 3 pressurised dual seal. 通常用于带压双封

During normal operation, circulation is

maintained by an internal pumping ring. 在正常操作情况下，通过腔内的泵效环维持循环

The reservoir pressure is greater than the process pressure being sealed.罐内压力通常高于被密封介质压力

External reservoir providing pressurised barrier fluid for the outer seal of an pressurised dual seal

arrangement. 外部储罐对带压双封的外密封起隔离液的效果

Drain



Typically used with an Arrangement 3 pressurised dual seal. 通常用于带压双封

During normal operation, circulation is maintained by an external pump or pressure system. 在正常操作情况下，通过外部的泵或压力系统维持循环

The circulating barrier fluid pressure is greater than the process pressure being sealed. 循环隔离液的压力高于被密封介质的压力

External barrier fluid system providing pressurised barrier fluid for the outer seal of an pressurised dual seal arrangement

外部隔离液系统对带压双封的外密封提供带压隔离液


Safe to use, handle, store 储藏、操作、使用安全可靠 Stable liquid at ambient temperatures 在室温下，性能稳定 Not a VOC, VHAP or other regulated compound 不易挥发、非有毒物质 Non flammable 不易燃烧 Non foaming when pressurised 高于常压时，不易起泡 Clean and good lubricity 干净且有较好的润滑性 Compatible with process fluid 与工艺流体有互容性 Compatible with seal materials 与密封材料相一致 Good heat transfer properties 有好的传热性能 Good flow qualities at very low temperatures 在低温下，有好的流动性 Low solubility of gas 对气体有较低的溶解性 Local availability 当地容易获得 Low cost 成本低

VOC : Volatile Organic CompoundVHAP : Volatile Hazardous Air Polutants


Tapped connections for the purchaser’s use在接口处攻螺纹，以方便用户使用

Point to Note for API Plan 61:对于 API plan 61 须注意 :

Typically this plan is used when the purchaser is to provide fluid (such as steam, gas, or water ) to an auxiliary sealing device.

通常在买方能给密封辅助系统提供流体（如蒸汽、气体或水）的情况下，才采用该方案


Points to Note for API Plan 62: 对于 API plan 62 须注意 :

The quench may be required to prevent solids from accumulating on the atmospheric side of the seal.增加吹扫口以防止在密封大气侧有颗粒的积累

Typically used with a close-clearance throttle bushing.

普遍使用节流衬套


Single Seal Quench from External Source单密封通过外部急冷

API 682 2nd Edition API 682 第二版New Piping Plans 新的冲洗方案

Plan 14 (Plan 11+13) 冲洗方案 14 Plan 53’s - Arrangement 3, Contacting Wet (CW) Seals 53 方案 -

排列方案 3 ，接触式湿密封 53a – traditional configuration 传统构造 53b – bladder accumulator 蓄能器 53c – piston pot/ accumulator 活塞 / 蓄能器

Containment Seal 二次辅助密封 Plan 72 – Arrangement 2 w/ Containment Seal (CS) Plan 75 – Arrangement 2 w/ Containment Seal (CS) Plan 76 – Arrangement 2 w/ Containment Seal (CS)

Gas Barrier Seals 气体 Plan 74 – Arrangement 3, Non-Contacting (NC) Seals 排列方式

3 ，非接触式密封

Plan 53a (A.4.12)

Arrangement 3, Contacting Wet (CW) Seals 排列方式 3 ，接触式湿密封 Dual Pressurised (Double) Seals 带压双封 Utilises direct nitrogen blanket for pressure 利用氮气层来增压 due to nitrogen entrainment in the barrier liquid API 682 limits the maximum nitrogen pressure to 10 barg, JC recommendation is

maximum nitrogen pressure 21 barg, as long as the barrier fluid temperature is less than 120°C API 682 限制了氮气的最大压力为 10barg, 约翰克兰建议只要隔离液温度小于 120 度，最大氮气压力 21barg,

API 682 2nd Edition API 682 第二版 New Piping Plans 新的冲洗方案

Plan 53b (A.4.12)

Arrangement 3, Contacting Wet (CW) Seals 排列方式 3 ，接触式湿密封

Dual Pressurised (Double) Seals 带压双封 Utilizes bladder accumulator for pressure 利用蓄能器来增压 Bladder eliminates nitrogen contact with barrier liquid 蓄能器把氮

气与隔离液分开 Allows for higher pressure applications 允许高压力应用

Configuration Includes:– Accumulator 蓄电池– Pressure Indicator 压

力显示器– Pressure Switch 压力

开关– Heat Exchanger 换热

器

BI

BO

TI BIBO

FWhen

Specified


Plan 53c (A.4.12)

Arrangement 3, Contacting Wet (CW) Seals 排列方式 3 ，接触式湿密封

Dual Pressurised (Double) Seals 带压双封 Utilizes piston pot for pressure 利用活塞增压

BI

BO

BIBOF

When Specified


Plan 53c (A.4.12)

Allows for higher pressure applications 允许高压力应用

Configuration includes: 构造包括– Piston pot 活塞– Pressure indicator 压力显示器– Pressure switch 压力开关‘– Heat exchanger 换热器– Level switch 电平开关

Piston pot eliminates nitrogen contact with barrier liquid 活塞缸阻断了隔离液与氮气的连接 Piston provides constant pressure ratio to seals (1.1:1) 活塞给密封提供持续的压力比率

Spring 弹簧


Barrier Fluid Temperature (7.3.4.1.1)

隔离流体温度

Liquid barrier systems shall be designed such that that maximum temperature differential between the barrier fluid inlet and outlet immediately adjacent to the seal chamber is:

设计隔离液系统允许的温差不一样，入口和出口温差不一样 8 degree C for glycol /water or diesel barrier fluids; and 对于水，乙

二醇，柴油隔离液，允许最大温差 8 度 16 degree C for mineral oil barrier fluid 矿物油隔离液允许最大温差

16 度

Plan 11 with Plan 53

Arrangement 3 may use Plan 11 & 53 排列方式 3 可以用 11&53 方案 Improved heat transfer 增加换热 Reverse pressure capability 压力转换能力

“Back to Back ” seals uses Plan 53背对背密封用 53方案


Plan 72 (A.4.16) Arrangement 2, w/ Containment Seal (CS) 排列方式 2 ，辅助二次密封 Dual Un-Pressurised (Tandem) Seals 不带压双封

– Dry-running secondary containment seal 干运转二次辅助密封 Low pressure nitrogen sweep (purge) 低压氮气吹扫

– Sweeps primary leakage to collection system 主密封泄漏的东西排放到收集系统里

– Dilutes primary leakage to lower emission levels 稀释泄漏的东西 Used in conjunction with Plan 75 or 76 ，与 75 方案获 76 方案一起使用

CSV: containment seal ventCSD: containment seal DrainGBI: gas buffer inletFIL: coalescing filter

CSV: containment seal ventCSD: containment seal DrainGBI: gas buffer inletFIL: coalescing filter


Plan 74 (A.4.17) Arrangement 3, Non-contacting Seals (NC) 排列方式 3 ，非接触式密封 Dual Pressurised (Double) Gas Barrier Seals 带压 Nitrogen gas barrier 氮气隔离

1.75 - 2 bar (25-30 psi) above seal chamber pressure 密封腔压力 1.75-2bar

– Zero emissions 零泄漏 Essentially a T2800 panel 2800类型控制面板

GBI: gas buffer inlet GBO: gas buffer outlet (NC)(used only to depressurize)

GBI: gas buffer inlet GBO: gas buffer outlet (NC)(used only to depressurize)


Plan 75 (A.4.18) Arrangement 2, w/ Containment Seal (CS) 排列方案 2 ，二次辅助密封 Dual Un-Pressurised (Tandem) Seals 双无压密封

– Dry-running secondary 辅助密封干运转 Condensate collection reservoir (8.6.5.2) 冷凝液收集罐

– Used when primary seal leakage may condense ( does not completely vaporize) 用于从主密封泄漏出来的可冷凝的工况

May be used in conjunction with Plan 72 或许和 72 方案一起使用


Plan 76 (A.4.19)

Arrangement 2, w/ Containment Seal (CS) 排列方式 2 ，二次辅助密封 Dual Un-Pressurised Seals (Dry-running secondary) 双无压密封 Primary leakage routed to flare or vent

– Used when primary seal leakage will not condense (completely vaporizes) 用于从主密封泄漏出的不可冷凝的工况

– Essentially a 48SC or 28LD panel leakage detection May be used in conjunction with Plan 72 或许和 72 方案一起使用


密封安装第三部分

在安装前，不要拆开密封不要接触或碰撞密封面将密封面向上放置密封

放在柔软的棉质纸上密封面不要朝下或侧置

安装密封时应使手保持干净在把动静环放置在一起前，要小心地用棉质纸和溶剂

来擦洗密封面密封面上不要使用润滑油

密封系统的运行及其可靠性受密封安装公差的影响。应保证密封安装公差不超过所要求的极限。

表面粗糙度及尺寸检查表面粗糙度及尺寸检查

注 1 检查轴及密封腔的尺寸和如图所虱的粗糙度。

倒角 1.5（与水平方向） x 20°

表面粗糙度参考左边表格

0.8

密封类型表面粗糙度动态 O 形圈 0.3/0.6 µm Ra

(研磨 )

静态 O 形圈 0.2/1.2 µm Ra ( 车 )

橡胶波纹管 0.8/1.2 µm Ra ( 车 )

PTFE 波纹管 0.8/1.2 µm Ra ( 车 )

动态及静态楔形环

0.1/0.25 µm Ra(研磨 )

轴跳的检查轴跳的检查

注 2 测量密封安装处的轴跳轴跳最大值不超过 0.05mm FIM.

用手使轴旋转记录指示仪上的读数

轴窜量的检查轴窜量的检查

注 3 轴窜量的最大值不超过 0.08mm FIM 。密封通过处的轴及轴套要去除毛刺和尖角。

用手使轴沿轴向移动记录指示仪上的读数

垂直度检查垂直度检查

注 4 垂直度最大值在密封腔直径每 10mm距离上不超过 0.005mm* (* 对波纹管密封不超过 0.002mm )


同轴度检查同轴度检查


注 5 同轴度最大值不超过 0.13mm FIM.

注 1 检查轴及密封腔的尺寸及表面粗糙度

注 2 检查密封安装处的轴跳轴跳最大值不超过 0.05mm FIM.



注 5 同轴度最大值不超过 0.13mm FIM.

轴跳

注 4 垂直度最大值在密封腔直径每 10mm距离上不超过 0.005mm


垂直度

注 3 轴窜最大值不超过 0.08mm FIM. 密封通过处的轴及轴套要去除毛刺和尖角

用手使轴沿轴向移动记录指示仪上的读数

轴窜同轴度

0.8

倒角 1.5（与水平方向） x 20°

0.8

表面粗糙度及尺寸

轴向调整量 < = 0.002” (0.05 mm) 径向调整量 < = 0.003” (0.075 mm)

电机

用垫片进行调整

电机

轴向及径向调整量 < = 0.1 mm (0.0039”)

电机

不合理的管线可能会引起轴的扭曲并降低密封寿命安装新泵时，应保证正确的管线进出口连接在连接管线前，对联轴器进行调整检查将指示仪放入指定位置并重新调整管线如出现震动现象，有必要重新进行管线的设置直至螺栓能容易地进行安装而不发生变形

集装式密封的安装

集装式密封的安装拆泵 - - - 装配前的准备

密封

密封


如有必要的话，先安装轴套，通常钩式轴套不属于集装式系列

集装式密封的安装将密封安装在轴或辅助轴套上此时，不要将集装式密封锁紧在轴上


安装密封腔。通过密封时，小心密封腔不要碰撞密封头。将螺栓安装到位。

集装式密封的安装用螺栓将端盖和密封腔贴合在一起。一定要检查

端盖和密封腔的垂直度。


安装叶轮，锁紧叶轮。进行各方位的调整来保证叶轮和密封腔间的间隙


拧紧螺栓使密封驱动环锁紧在轴或轴套上。除去定位片。

集装式密封的安装将带有垫片的泵体安装到位，拧紧螺栓，检查是否泄漏。

4 simple installation steps 简单的安装四步骤

1

4

3

2

having positioned the shaft and carried out equipment checks,

1 slide seal cartridge onto the shaft

2 tighten gland nuts evenly

3 tighten drive collar set screws

4 remove setting spacers

Cartridge Seals 集装式密封

密封失效大致判断第四部分

Seal Faces 密封面 Loss of Flexibility灵活性丧失 Secondary Sealing Elements 二次密封 Material Compatibility材料兼容性

New新的

Worn磨损

Face Damage: Wear out 面破坏 : 磨损

Face Damage: Heat Checking面破坏 : 热检测

Leakage decomposes or solidifies and locks primary ring in place此位置的泄漏产生结垢或者固化使动环挂起

Loss of Flexibility: Hangup丧失灵活性 :挂起

Secondary Sealing Element Problems二次密封问题

Cuts overheated compatibility with fluid 消除过热并保证与介质的兼容性

Material Compatibility of Faces and Hardware 摩擦面和金属件的材料兼容性

Corrosion腐蚀 Wear 磨损

No Seal Can Handle

All Applications没有能够适合所有工况的

密封

Documents

西部管道密封培训