深度分析CCPP系統中濕蒸氣之沖蝕行為種類與P9x高能管線防護優化研究(In-Depth Analysis of Wet Steam Erosion Behaviors and Protection Optimization for P9x High-Energy Piping in CCPP Systems)

/ Uncategorized / 作者:

一、 緒論與複循環發電廠管線劣化背景/I. Introduction and Background of Piping Degradation in Combined Cycle Power Plants

在現代化智慧電網與能源轉型的架構下，複循環火力發電廠（Combined Cycle Power Plant, CCPP）已從傳統的基載發電主力，轉變為承擔極端負載跟隨（Load-following）與頻繁起停（Start-stop cycling）的關鍵調度機組。隨著太陽能與風力發電等間歇性再生能源併網比例的急遽增加，電網淨負載呈現劇烈波動的「鴨子曲線」（Duck Curve）現象，迫使CCPP機組必須具備極高的運行靈活性1。然而，此種頻繁偏離最佳設計點的熱力循環操作模式，為廠內的高能管線系統（High-Energy Piping, HEP）帶來了前所未有的物理與化學劣化挑戰。 In the framework of modern smart grids and energy transition, Combined Cycle Power Plants (CCPP) have shifted from traditional baseload generators to critical dispatch units responsible for extreme load-following and frequent start-stop cycling. With the rapid increase in the grid integration of intermittent renewable energy sources, such as solar and wind, the net load exhibits a sharply fluctuating “Duck Curve” phenomenon, compelling CCPP units to maintain extremely high operational flexibility1. However, this thermodynamic operating mode, which frequently deviates from optimal design points, presents unprecedented physical and chemical degradation challenges for the plant’s High-Energy Piping (HEP) systems.

當高壓蒸汽輪機（HP Turbine）的負載驟降或啟動時，低壓汽機級數與高壓旁路系統中的蒸氣極易跨越熱力學上的飽和線（Wilson line），引發等熵膨脹並自發凝結為次微米級的濕蒸氣霧滴1。這些微小液滴在流經靜子葉片、管路縮孔或閥門等幾何限制區域時，會因慣性碰撞而於金屬表面凝結成連續水膜。隨後，在高速連續氣相的強烈剪切力作用下，水膜破裂並二次霧化為直徑從十微米至數百微米不等的大型二次液滴。二次液滴被流速高達每秒數百公尺的蒸氣流加速，挾帶巨大的動能猛烈撞擊管壁、彎頭外弧側（Extrados）及閥件內部，從而誘發極具破壞性的液滴撞擊沖蝕（Liquid Droplet Impingement Erosion, LDI）與流體加速腐蝕（Flow-Accelerated Corrosion, FAC）1。 When the load of the high-pressure (HP) steam turbine drops suddenly or during startup, the steam in the low-pressure turbine stages and the high-pressure bypass system easily crosses the thermodynamic saturation line (Wilson line). This triggers isentropic expansion and spontaneous condensation into sub-micron wet steam fog droplets1. As these tiny droplets flow through geometrically restricted areas, such as stator blades, pipe orifices, or valves, they collide due to inertia and condense into continuous water films on metal surfaces. Subsequently, under the intense shear force of the high-speed continuous gas phase, the water film ruptures and undergoes secondary atomization into large secondary droplets ranging from tens to hundreds of micrometers in diameter. Accelerated by steam flowing at hundreds of meters per second, these secondary droplets carry tremendous kinetic energy and violently impact pipe walls, the extrados of elbows, and internal valve components. This triggers highly destructive Liquid Droplet Impingement Erosion (LDI) and Flow-Accelerated Corrosion (FAC)1.

在CCPP系統中，承受此類極端高溫、高壓及高速雙相流體衝擊的主要材料，多為具備優異高溫潛變阻抗的改質麻田散鐵系鉻鉬鋼，如P91（X10CrMoVNb9-1）與P92鋼材。儘管這些高階合金材料在穩態高溫下表現出色，但在濕蒸氣沖蝕、熱疲勞、氫脆化以及銲接熱影響區（HAZ）的微觀組織劣化等多重耦合作用下，極易發生局部壁厚急遽減薄、管線穿孔甚至災難性的爆裂失效4。因此，本報告旨在全面深度剖析CCPP系統中濕蒸氣沖蝕行為之物理力學與流體化學機制，探討P9x系列高能管線在多重劣化機制下的材料脆弱性，並進一步基於宏觀幾何應力規範（ASME B31J）、微觀表面工程與二次水化學控制優化，提出系統性的管線防護優化與壽命預測策略。 In CCPP systems, the primary materials subjected to such extreme high-temperature, high-pressure, and high-speed two-phase fluid impacts are modified martensitic chromium-molybdenum steels, such as P91 (X10CrMoVNb9-1) and P92, which possess excellent high-temperature creep resistance. Although these advanced alloys perform exceptionally well under steady-state high temperatures, they are highly susceptible to rapid localized wall thinning, perforation, and even catastrophic burst failures under the multiple coupled effects of wet steam erosion, thermal fatigue, hydrogen embrittlement, and microstructural degradation in the heat-affected zone (HAZ) of welds4. Therefore, this report aims to comprehensively analyze the physical, mechanical, and fluid-chemical mechanisms of wet steam erosion in CCPP systems, explore the material vulnerabilities of P9x high-energy piping under multiple degradation mechanisms, and propose systematic piping protection optimization and life prediction strategies based on macroscopic geometric stress codes (ASME B31J), microscopic surface engineering, and secondary water chemistry control.

二、 濕蒸氣流場特徵與液滴撞擊沖蝕（LDI）之物理數學模型/II. Wet Steam Flow Characteristics and Physical-Mathematical Models of Liquid Droplet Impingement (LDI) Erosion

在探討管線防護前，必須先精確解析濕蒸氣液滴撞擊固體表面的瞬態物理過程。液滴撞擊沖蝕（LDI）並非單純的摩擦損耗，而是一種由極高應變率下的流體可壓縮性所引發的複雜機械疲勞與衝擊波破壞機制。 Before discussing piping protection, it is essential to accurately analyze the transient physical processes of wet steam droplets impacting solid surfaces. Liquid Droplet Impingement Erosion (LDI) is not merely frictional wear; rather, it is a complex mechanical fatigue and shockwave destruction mechanism triggered by fluid compressibility at extremely high strain rates.

2.1 液滴撞擊與水錘壓力效應 / 2.1 Droplet Impingement and Water Hammer Pressure Effects

當高速二次液滴以超音速或近音速撞擊金屬管壁表面時，接觸瞬間液體因無法及時側向排開而表現出高度的可壓縮性。根據流固耦合的力學原理，此撞擊會在液滴內部與液固介面處激發出極高強度的壓力脈衝，被稱為「水錘壓力」（Water Hammer Pressure）1。Cook率先提出水錘壓力的基礎數學模型，指出其遠大於穩態流體積壓；隨後，Heymann等人將固體目標物的激波傳遞行為納入考量，推導出更精確的最大瞬態接觸壓力邊界條件模型： When high-speed secondary droplets impact the metal pipe wall at supersonic or near-sonic speeds, the liquid exhibits high compressibility at the moment of contact because it cannot be displaced laterally in time. According to fluid-structure interaction principles, this impact excites ultra-high-intensity pressure pulses inside the droplet and at the liquid-solid interface, known as “Water Hammer Pressure”1. Cook first proposed the basic mathematical model for water hammer pressure, noting it is far greater than steady-state fluid stagnation pressure. Subsequently, Heymann and others incorporated the shockwave transmission behavior of solid targets, deriving a more accurate boundary condition model for maximum transient contact pressure:

Pwh=(Vimpact (ρw Cw ))/(1+(ρw Cw)/(ρm Cl,m ))

在此公式中，Vimpact 代表液滴的撞擊速度，ρw 與 Cw 分別為液體的密度與聲速（其中動態聲速 Cw 會隨撞擊速度上升而變化，可表示為Cw=Cw0+kVimpact），ρm 與 Cl,m 則代表目標金屬基材的密度與聲波傳遞速度4。 In this formula, Vimpact represents the droplet impact velocity, ρw and Cw are the liquid density and speed of sound respectively (where the dynamic speed of sound Cw varies with impact velocity and can be expressed as Cw=Cw0+kVimpact), and ρm and Cl,m denote the density and sound wave propagation velocity of the target metal substrate4.

2.2 應力波傳遞與微觀疲勞破壞機制 / 2.2 Stress Wave Propagation and Microscopic Fatigue Failure Mechanisms

水錘壓力的產生僅持續數微秒，但其釋放的強烈衝擊波會干擾目標金屬內部的機械平衡。衝擊波在固體材料內部會轉化為三種不同形式的應力波：沿縱向傳播的膨脹波（Dilatational wave）、沿橫向傳播的剪切波（Shear wave），以及沿材料表面擴散的高振幅雷利表面波（Rayleigh surface waves）7。這些應力波的傳播速度取決於金屬的彈性模數、蒲松比（Poisson’s ratio）與密度。 The generation of water hammer pressure lasts only a few microseconds, but the intense shockwaves it releases disrupt the mechanical equilibrium inside the target metal. Inside the solid material, the shockwaves convert into three different forms of stress waves: dilatational waves propagating longitudinally, shear waves propagating transversely, and high-amplitude Rayleigh surface waves spreading along the material’s surface7. The propagation speeds of these stress waves depend on the metal’s elastic modulus, Poisson’s ratio, and density.

當應力波的振幅與持續時間超過材料的動態斷裂強度時，便會在金屬表面與次表面微觀缺陷處引發應力集中。雷利波的表面剪切作用特別容易撕裂材料晶界，誘發塑性變形與微裂紋（Microcracks）的萌生。隨著液滴的循環撞擊，這些微裂紋會依循疲勞機制不斷擴展並交會，最終導致巨觀的金屬剝落（Spalling）與質量流失。根據Heymann與ASTM G73-10標準的分類，典型的水滴沖蝕曲線（S型曲線）可劃分為五個關鍵階段：潛伏期、加速期、最大穩態沖蝕率期、減速期以及終端期（或災難期）7。 When the amplitude and duration of the stress waves exceed the dynamic fracture strength of the material, stress concentration is induced at surface and sub-surface microscopic defects. The surface shearing action of Rayleigh waves is particularly prone to tearing material grain boundaries, inducing plastic deformation and the initiation of microcracks. With cyclic droplet impacts, these microcracks continuously propagate and intersect following fatigue mechanisms, ultimately leading to macroscopic metal spalling and mass loss. According to the classifications by Heymann and the ASTM G73-10 standard, a typical water droplet erosion curve (S-curve) can be divided into five key stages: incubation period, acceleration stage, steady-state maximum erosion rate stage, deceleration stage, and terminal (or catastrophic) stage7.

2.3 疲勞壽命與沖蝕預測之數值模型（Springer & Oka Model） / 2.3 Numerical Models for Fatigue Life and Erosion Prediction (Springer & Oka Model)

為了在工程設計中精確預測高能管線的沖蝕壽命，計算流體力學（CFD）被廣泛應用於模擬氣液兩相流場。在預測金屬疲勞壽命方面，源自航空領域的Springer疲勞模型被廣泛修改並應用於高壓蒸氣管線的壽命預估。該模型引入了塗層或金屬表面的等效沖蝕阻力參數S，其公式形式包含： To accurately predict the erosion life of high-energy piping in engineering design, Computational Fluid Dynamics (CFD) is widely used to simulate gas-liquid two-phase flow fields. For predicting metal fatigue life, the Springer fatigue model, originating from the aviation sector, has been widely modified and applied to the life estimation of high-pressure steam piping. This model introduces an equivalent erosion resistance parameter S for coatings or metal surfaces, formulated as:

S=[4(b-1)σ]/(1-2ν)(2k|ψ|+1)

其中 σ 為材料強度參數，ν 為蒲松比，b 為S-N疲勞曲線的斜率參數，k 與 ψ 則分別反映了機械波的平均反射次數與塗層-基材界面的相對阻抗8。現代數值分析更傾向結合Oka沖蝕模型，依據不同的撞擊角度估算非正向撞擊下的質量流失率，進而建構更精確的三維壁厚減薄預測工具1。 Where σ is the material strength parameter, v is Poisson’s ratio, b is the slope parameter of the S-N fatigue curve, and k and ψ reflect the average number of mechanical wave reflections and the relative impedance of the coating-substrate interface, respectively8. Modern numerical analyses increasingly integrate the Oka erosion model to estimate mass loss rates under non-normal impacts at varying angles, thereby constructing more precise 3D wall thinning prediction tools1.

三、 CCPP高能管系之流體加速腐蝕（FAC）與兩相流劣化機制/III. Flow-Accelerated Corrosion (FAC) and Two-Phase Flow Degradation Mechanisms in CCPP High-Energy Piping

液滴撞擊沖蝕（LDI）代表了純機械性的破壞，而在實際的CCPP運作環境中，純機械破壞往往與電化學腐蝕形成惡性耦合，其中最具威脅性的即為流體加速腐蝕（Flow-Accelerated Corrosion, FAC）。FAC的發生，源於高速流體及其挾帶的湍流剪切力，不斷剝離並溶解金屬表面自然生成的保護性氧化層（如磁鐵礦Fe3O4），使底層金屬持續裸露於腐蝕環境中11。 Liquid Droplet Impingement (LDI) erosion represents a purely mechanical failure. However, in actual CCPP operating environments, mechanical destruction often couples maliciously with electrochemical corrosion. The most threatening among these is Flow-Accelerated Corrosion (FAC). FAC occurs when high-speed fluids and the turbulent shear forces they carry continuously strip and dissolve the naturally formed protective oxide layer (e.g., magnetite, Fe3O4) on the metal surface, continuously exposing the underlying metal to the corrosive environment11.

3.1 單相與兩相FAC之特徵對比 / 3.1 Characteristics Comparison of Single-Phase and Two-Phase FAC

在熱回收蒸汽產生器（HRSG）與汽輪機周邊管線中，FAC依據流體狀態可區分為兩大類： In Heat Recovery Steam Generators (HRSG) and turbine peripheral piping, FAC can be classified into two main categories based on fluid state:

項目 / Item 單相FAC / Single-Phase FAC 兩相FAC / Two-Phase FAC
流體狀態 / Fluid State 完全為液態水相。 / Completely liquid water phase. 蒸汽與液滴共存的混合相。 / Mixed phase of steam and droplets.
易發位置 / Prone Locations 給水系統、省煤器。 / Feedwater systems, economizers. 低壓蒸發器、加熱器疏水管。 / LP evaporators, heater drains.
驅動機制 / Driving Mechanism 湍流、溶氧不足與低pH值。 / Turbulence, low DO, and low pH. 液滴高速撞擊與液相嚴重酸性化。 / Droplet impact and severe liquid acidification.
巨觀形貌 / Macroscopic Morphology 均勻減薄的「橘皮狀」表面。 / Uniformly thinned “orange peel” surface. 局部點蝕、深溝槽，常與LDI疊加。 / Localized pitting, trenching, often overlapping with LDI.

(資料綜合整理自 EPRI 指南與業界水化學分析13) (Data summarized from EPRI guidelines and industry water chemistry analysis13)

3.2 兩相FAC的微環境化學與汽液相分配效應 / 3.2 Micro-Environmental Chemistry of Two-Phase FAC and Vapor-Liquid Partitioning Effects

兩相FAC之所以在濕蒸氣管線中極難控制，主要歸咎於「汽液相分配效應」（Vapor-Liquid Partitioning）。在傳統的水化學處理中，電廠常注入氨水（Ammonia）作為pH值控制劑。然而，在低壓汽鼓或蒸發器中，氨水具有極高的揮發性，絕大部分的氨會隨蒸氣進入汽相，留下極度缺乏鹼性物質的液態水滴或水膜14。 Two-phase FAC is extremely difficult to control in wet steam piping primarily due to the “Vapor-Liquid Partitioning” effect. In traditional water chemistry treatment, power plants often inject ammonia as a pH control agent. However, in low-pressure drums or evaporators, ammonia is highly volatile; the vast majority of ammonia enters the vapor phase with the steam, leaving behind liquid water droplets or films that severely lack alkaline substances14.

這些缺乏氨水保護的水滴不僅pH值大幅下降（酸性化），且因脫氣作用，內部幾乎無溶解氧（DO）。在缺乏溶氧且呈現微酸性的高溫液態薄膜內，碳鋼表面的鐵原子極易失去電子而溶解，形成極高的鐵離子釋放率3。當閥門處於部分開度或流體行經複雜管件時，這些具備高腐蝕性的酸性液滴會隨高速主流偏離，猛烈撞擊彎頭外側，造成FAC與LDI的惡性耦合，管壁減薄率可達每年數公釐之多1。 These ammonia-depleted water droplets not only experience a significant drop in pH (acidification) but also contain almost no dissolved oxygen (DO) due to degassing effects. Within these high-temperature, slightly acidic, and oxygen-deprived liquid films, iron atoms on the carbon steel surface readily lose electrons and dissolve, leading to an extremely high iron ion release rate3. When valves are partially open or fluid flows through complex fittings, these highly corrosive acidic droplets deviate from the high-speed main flow and violently impact the extrados of elbows. This creates a malicious coupling of FAC and LDI, resulting in wall thinning rates that can reach several millimeters per year1.

四、 P91/P92高能管線之材料冶金特性與多重劣化機制/IV. Metallurgical Properties and Multiple Degradation Mechanisms of P91/P92 High-Energy Piping

為了承受CCPP的高溫高壓，業界廣泛採用P9x系列高階鉻鉬合金鋼。雖然其具備卓越的潛變抗力，但在水化學腐蝕、銲接熱循環與機械疲勞交織的環境中，材料的微觀結構會暴露出致命的脆弱性。 To withstand the high temperatures and pressures in CCPP, the industry widely employs P9x series advanced chromium-molybdenum alloy steels. While possessing exceptional creep resistance, the materials’ microstructures expose fatal vulnerabilities in environments where water chemistry corrosion, welding thermal cycles, and mechanical fatigue intertwine.

4.1 P91微觀組織與高溫氧化/腐蝕動力學 / 4.1 Microstructure and High-Temperature Oxidation/Corrosion Kinetics of P91

P91鋼（X10CrMoVNb9-1）是一種含有9% Cr、1% Mo，並添加微量鈮（Nb）、釩（V）及控制氮（N）含量的麻田散鐵鋼。在交貨狀態下，P91經正常化與回火處理後，基體內均勻析出富含V/Nb的M23C6 型碳化物與 MX 型碳氮化物。這些奈米級析出物藉由釘扎差排運動，提供了極佳的高溫潛變斷裂強度4。然而，若溫度超過約620 °C，其最大容許應力將急降至50 MPa以下，甚至遜於304奧氏體不銹鋼4。 P91 steel (X10CrMoVNb9-1) is a martensitic steel containing 9% Cr, 1% Mo, with micro-additions of niobium (Nb), vanadium (V), and controlled nitrogen (N) content. In the as-delivered state, following normalizing and tempering treatments, V/Nb-rich M23C6 carbides and MX carbonitrides precipitate uniformly within the matrix. These nanoscale precipitates provide excellent high-temperature creep rupture strength by pinning dislocation movements4. However, if the temperature exceeds approximately 620 °C, its maximum allowable stress plummets below 50 MPa, making it even inferior to 304 austenitic stainless steel4.

在高溫含水蒸氣的環境下，水蒸氣分子會穿透氧化層，發生競爭性吸附作用，伴隨著揮發性氫氧化鐵的生成，觸發快速的氧化反應，使緻密的富鉻氧化層轉變為疏鬆的富鐵氧化層12。這種增厚的氧化層在LDI的高頻衝擊下極易發生脆性剝落，形成加速管壁減薄的毀滅性循環12。 In high-temperature environments containing water vapor, vapor molecules penetrate the oxide scale and undergo competitive adsorption. Accompanied by the formation of volatile iron hydroxides, this triggers rapid oxidation reactions, transforming the dense chromium-rich oxide layer into a porous iron-rich oxide layer12. Under the high-frequency impacts of LDI, this thickened oxide layer is highly susceptible to brittle spalling, forming a devastating cycle of accelerated wall thinning12.

4.2 銲接熱影響區與第四型潛變裂紋（Type IV Cracking） / 4.2 Weld Heat-Affected Zones and Type IV Cracking

在P91與P92管線系統中，銲接接頭尤其是熱影響區（HAZ）是最脆弱的一環。長期服役於高溫（如600 °C）及系統應力下，極易在HAZ的細晶區或相間臨界區萌生「第四型裂紋」（Type IV Cracking）6。此劣化導致P91跨銲道的潛變斷裂強度大幅折損，尤其在承受環向應力的縱向直縫銲道中，爆管風險呈指數級上升6。嚴格控制銲後熱處理（PWHT，如 760 °C 恆溫 120 分鐘）是恢復材料韌性與安全性的關鍵21。 In P91 and P92 piping systems, weld joints—especially the Heat-Affected Zones (HAZ)—are the most vulnerable links. Operating long-term at high temperatures (e.g., 600 °C) under system stress easily initiates “Type IV Cracking” in the fine-grained or intercritical regions of the HAZ6. This degradation significantly compromises the cross-weld creep rupture strength of P91. Particularly in longitudinal seam welds subjected to hoop stress, the risk of pipe bursting increases exponentially6. Strict control of Post-Weld Heat Treatment (PWHT, such as 760 °C holding for 120 minutes) is crucial for restoring material toughness and safety21.

4.3 異種金屬銲接（DMW）之複合劣化機制 / 4.3 Complex Degradation Mechanisms of Dissimilar Metal Welds (DMW)

當P91需與奧氏體不銹鋼（如316H）進行異種金屬銲接（DMW）時，由於碳遷移（Carbon Migration）、熱膨脹係數不匹配（CTE Mismatch，引發熱疲勞）與氧化物缺口（Oxide Notching）等多重協同機制的交互作用，DMW通常被視為發電廠中最易失效的節點23。 When P91 is welded to austenitic stainless steel (such as 316H) to form Dissimilar Metal Welds (DMW), it is generally considered the most failure-prone node in a power plant. This is due to the interactive effects of multiple synergistic mechanisms, including carbon migration, Coefficient of Thermal Expansion (CTE) mismatch (which induces thermal fatigue), and oxide notching23.

4.4 氫脆化與負載耦合腐蝕疲勞 / 4.4 Hydrogen Embrittlement and Load-Coupled Corrosion Fatigue

P91鋼的高強度麻田散鐵結構對「氫脆化」（Hydrogen Embrittlement, HE）極度敏感。在恆定負載與充氫的雙重條件下，材料的斷裂伸長率與斷面收縮率會出現斷崖式崩跌（如伸長率降至 3.4%）。這意味著管線在氫與應力的耦合下，會轉變為毫無預警的混合「韌-脆性破壞」，極易引發瞬間爆管4。 The high-strength martensitic structure of P91 steel makes it extremely sensitive to “Hydrogen Embrittlement” (HE). Under dual conditions of constant load and hydrogen charging, the material’s elongation at fracture and reduction of area experience a cliff-like plunge (e.g., elongation dropping to 3.4%). This means that under the coupling of hydrogen and stress, the piping transforms into an unpredictable mixed “ductile-brittle failure” mode, making it highly prone to instantaneous bursting4.

五、 基於宏觀幾何、 ASME B31J 規範與實務工法之管線優化/V. Piping Optimization Based on Macroscopic Geometry, ASME B31J Code, and Practical Fabrication Methods

面對嚴峻的複合劣化，單一防護措施已無法保障管線安全。在宏觀管線設計層次，透過流場幾何改造與依循最新應力規範，並結合前瞻的管件加工技術，可從源頭大幅削減流體衝擊力與熱疲勞應力。 Faced with severe combined degradation, singular protective measures can no longer guarantee piping safety. At the macroscopic piping design level, utilizing flow geometry modifications, adhering to the latest stress codes, and integrating forward-looking pipe fabrication technologies can drastically reduce fluid impact forces and thermal fatigue stresses at the source.

5.1 盲通管（Blind Tees）的緩衝渦流設計 / 5.1 Buffer Vortex Design Using Blind Tees

現代優化設計導入了「盲通管」（Blind tees），將三通管的一端封閉以容納流體。計算流體力學模擬證實，當氣液兩相流進入盲通管時，部分流體會在盲端內部形成一個速度極低的「緩衝渦流區」（Buffer vortex zone）。高速襲來的破壞性液滴會被捲入並耗散動能，相較於傳統彎頭，盲通管設計可使最大沖蝕率驟降40%以上1。 Modern optimization designs introduce “Blind tees” (plugged tees), closing one end of a tee to accommodate fluid. Computational fluid dynamics simulations verify that when gas-liquid two-phase flows enter a blind tee, a portion of the fluid forms a very low-velocity “buffer vortex zone” inside the plugged end. Destructive high-speed incoming droplets are drawn in, dissipating their kinetic energy. Compared to traditional elbows, blind tee designs can plunge the maximum erosion rate by over 40%1.

5.2 3D/5D 冷作彎管工法與 ASME B31J 規範之應用 / 5.2 3D/5D Cold Bending Methods and Application of ASME B31J Code

傳統的對銲彎頭（小曲率半徑）會加劇迪安渦流（Dean vortices）與銲道劣化風險。導入具備大型曲率半徑的 3D 或 5D CNC 冷作彎管工法，並依據 ASME B31J 規範解析，能直接消除高風險的環向銲道，並大幅優化應力強度因子（SIF）與提升管系整體柔性（Flexibility），緩解熱疲勞1。 Traditional butt-welded elbows (with small curvature radii) exacerbate Dean vortices and the risk of weld degradation. Introducing 3D or 5D CNC cold bending methods with large curvature radii, analyzed according to the ASME B31J code, directly eliminates high-risk circumferential welds. Furthermore, it significantly optimizes the Stress Intensification Factor (SIF) and enhances overall piping flexibility, alleviating thermal fatigue1.

5.3 業主（台電）對於 P91/P92 蒸氣管線選取 3D/5D 彎徑之決策思維 / 5.3 Taipower’s Decision-Making Rationale for Selecting 3D/5D Bends for P91/P92 Steam Piping

作為發電業主的台灣電力公司（台電），其決策核心在於追求「全壽命週期成本」（LCC）極小化與「機組絕對安全性」。台電傾向採納「以彎代銲」的 3D/5D 冷作彎管工法，此決策奠基於最新 ASME B31J 規範。一體成型的彎管大幅減少了廠內環向銲道，直接降低了萌生Type IV潛變裂紋的風險，同時減少非破壞檢測（NDE）工作量，提升機組可用率30。 As a power generation owner, Taiwan Power Company (Taipower) centers its decision-making on minimizing Life Cycle Cost (LCC) and maximizing “absolute unit safety.” Taipower tends to adopt the 3D/5D cold bending method of “replacing welds with bends,” a decision grounded in the latest ASME B31J code. One-piece manufactured bends drastically reduce the number of circumferential welds in the plant, directly lowering the risk of Type IV creep cracks. Simultaneously, it reduces Non-Destructive Examination (NDE) workloads, boosting unit availability30.

5.4 EPC 承包商對於 P91/P92 管線選擇 3D/5D 彎徑工法之考量 / 5.4 EPC Contractors’ Considerations for 3D/5D Bending on P91/P92 Piping

從EPC承包商視角出發，導入 3D/5D 彎管工法能將大量管線加工轉移至工廠內進行預製（Prefabrication）。這巨幅降低了現場的高空銲接作業與鷹架搭設成本，縮短工期，並有效規避因複雜銲接瑕疵重工而帶來的合約逾期風險30。 From the perspective of Engineering, Procurement, and Construction (EPC) contractors, adopting 3D/5D bending methods allows a vast amount of pipe processing to be shifted to factory prefabrication. This massively cuts down on site high-altitude welding operations and scaffolding costs, shortens project timelines, and effectively mitigates the risk of contract delays caused by reworking complex welding defects30.

5.5 CCPP 3D/5D 彎徑在潁璋工程「三合一工法」之實務效益 / 5.5 Practical Benefits of the Ying Zhang Engineering “Three-in-One Method” for 3D/5D Bends in CCPP

針對厚壁高強度的P91合金，彎曲應變過大易造成材質劣化。潁璋工程（Ying Zhang Engineering）提出了「三合一工法」：結合「CNC 數控冷作彎管」、「感應加熱彎後熱處理（IH-PBHT）」與「數位化模組管理」。透過精準可控的IH-PBHT消除殘餘應力並恢復母材韌性，不僅完美落實了「以彎代銲」，更確保了 P91 彎管在雙相流環境中的長壽命效益32。 For thick-walled, high-strength P91 alloys, excessive bending strain easily degrades the material. Ying Zhang Engineering proposed a “Three-in-One Method,” combining “CNC Cold Bending,” “Induction Heating Post-Bend Heat Treatment (IH-PBHT),” and “Digital Module Management.” By utilizing precise and controllable IH-PBHT to eliminate residual stresses and restore parent metal toughness, this method not only perfects the “replacing welds with bends” concept but also ensures the long-life benefits of P91 bends in two-phase flow environments32.

六、 微觀表面工程與介面強化技術/VI. Microscopic Surface Engineering and Interface Strengthening Technologies

在閥芯內部等局部熱點，導入先進的金屬陶瓷或鈷基合金表面塗層，是阻絕沖蝕波的最後防線。 At localized hotspots such as valve internals, introducing advanced cermet or cobalt-based alloy surface coatings serves as the final defense line against erosion shockwaves.

6.1 Stellite 6 鈷基合金之「應變誘發相變」增韌機制 / 6.1 “Strain-Induced Phase Transformation” Toughening Mechanism of Stellite 6 Cobalt Alloy

Stellite 6 抵禦LDI高頻衝擊的核心奧秘在於其獨特的「應變誘發相變」（Strain-induced fcc-to-hcp phase transformation）。在承受高壓衝擊時，表層鈷基晶格會自發從面心立方結構（fcc）轉變為六方最密堆積結構（hcp）。此相變過程能大量吸收應變能，延長沖蝕潛伏期，並顯著提升表面硬度。冷噴塗（CGS）因能產生緻密無氧化物的塗層並保留初始fcc結構，展現出極佳的抗沖蝕壽命1。 The core secret behind Stellite 6 resisting high-frequency LDI impacts lies in its unique “Strain-induced fcc-to-hcp phase transformation.” Upon high-pressure impact, the surface cobalt-based lattice spontaneously transforms from a face-centered cubic (fcc) structure to a hexagonal close-packed (hcp) structure. This phase transformation absorbs vast amounts of strain energy, prolongs the erosion incubation period, and significantly increases surface hardness. Cold Gas Spraying (CGS) exhibits excellent erosion life as it produces dense, oxide-free coatings while retaining the initial fcc structure1.

6.2 雷射表面織構化（LST）與 WC-10Co-4Cr 介面強化 / 6.2 Laser Surface Texturing (LST) and WC-10Co-4Cr Interface Strengthening

為克服硬質塗層在水滴衝擊下易發生雷利波剝離的致命傷，研究利用 1064nm 光纖雷射對基材進行「雷射表面織構化」（LST）預處理。蝕刻出的微凹坑增加了接觸面積，形成強大的「機械互鎖效應」（Mechanical interlocking），成功阻斷了介面剝離，使WC-10Co-4Cr塗層的抗沖蝕能力大幅躍升 31.98%1。 To overcome the fatal flaw of hard coatings peeling off due to Rayleigh waves under droplet impact, studies utilize a 1064nm fiber laser for “Laser Surface Texturing” (LST) pre-treatment on the substrate. The etched micro-dimples increase contact area and form strong “mechanical interlocking.” This successfully blocks interface delamination, drastically boosting the erosion resistance of WC-10Co-4Cr coatings by 31.98%1.

七、 二次系統水化學控制優化與預測性維護（PdM）/VII. Secondary System Water Chemistry Optimization and Predictive Maintenance (PdM)

7.1 水化學處理機制的演進：從 AVT(R) 到 AVT(O) 與 OT / 7.1 Evolution of Water Chemistry Regimes: From AVT(R) to AVT(O) and OT

針對純鐵系的給水系統與HRSG，傳統的「全揮發性還原處理」（AVT(R)）無法防止FAC。現今標準強烈建議改採「全揮發性氧化處理」（AVT(O)）或「加氧處理」（OT）。利用微量氧氣與碳鋼表面反應，生成緻密強韌的「水合氧化鐵」或「赤鐵礦」，從而幾乎完全阻絕單相FAC的發生，其前提是給水必須保持極高純度13。 For all-ferrous feedwater systems and HRSGs, traditional “All-Volatile Treatment (Reducing)” (AVT(R)) fails to prevent FAC. Modern standards strongly recommend switching to “All-Volatile Treatment (Oxidizing)” (AVT(O)) or “Oxygenated Treatment” (OT). By utilizing trace amounts of oxygen to react with the carbon steel surface, a dense and tough “iron oxide hydrate” or “hematite” is formed, almost entirely eliminating single-phase FAC. The prerequisite is maintaining extremely high feedwater purity13.

7.2 有機中和胺（Neutralizing Amines）的導入 / 7.2 Introduction of Neutralizing Amines

為了解決氨水揮發導致兩相區水滴酸性化引發的兩相FAC，現代CCPP導入分配係數較佳的「有機中和胺」，如乙醇胺（ETA）。ETA在汽水分離時更容易殘留於水滴中，確保兩相區液滴pH值穩定大於9.8。業界常採用「90%氨水 + 10% ETA」混合胺策略，互補以達成全廠腐蝕最小化14。 To resolve two-phase FAC caused by droplet acidification resulting from ammonia volatilization, modern CCPPs introduce “neutralizing amines” with better partition coefficients, such as ethanolamine (ETA). During vapor-liquid separation, ETA is more likely to remain in the droplets, ensuring the pH of the two-phase region droplets remains stably above 9.8. The industry often employs a mixed amine strategy of “90% ammonia + 10% ETA,” complementing each other to minimize plant-wide corrosion14.

7.3 EPRI CHECWORKS 預測性維護整合系統 / 7.3 EPRI CHECWORKS Predictive Maintenance Integration System

EPRI開發的「CHECWORKS」平台能深度整合管線幾何、熱力學參數、材料成分與水化學監測數據。透過建立數字孿生模型，它能精確運算出管系的局部沖蝕率，結合動態壁厚補償，將電廠從「破漏後修補」升級為「預測性維護」（PdM），極大化機組的可用率1。 The “CHECWORKS” platform developed by EPRI deeply integrates piping geometry, thermodynamic parameters, material compositions, and water chemistry monitoring data. By building digital twin models, it accurately calculates localized erosion rates in piping systems. Coupled with dynamic wall thickness compensation, it upgrades power plants from “run-to-failure” to “Predictive Maintenance” (PdM), maximizing unit availability1.

八、 結論/VIII. Conclusion

本研究深入剖析指出，CCPP濕蒸氣沖蝕劣化是液滴撞擊產生的機械衝擊波與微酸性缺氧水滴造成的流體加速腐蝕（FAC）高度惡性耦合的結果。針對P9x高階鉻鉬鋼，氫脆化與銲接熱影響區的Type IV潛變裂紋更為致命。為徹底解決此威脅，本報告總結出立體防護策略： This research profoundly illustrates that CCPP wet steam erosion degradation is the highly malicious coupling of mechanical shockwaves generated by droplet impacts and Flow-Accelerated Corrosion (FAC) caused by slightly acidic, oxygen-deprived droplets. For P9x advanced chromium-molybdenum steels, hydrogen embrittlement and Type IV creep cracks in the weld heat-affected zone prove even more fatal. To thoroughly eliminate this threat, this report summarizes a multidimensional protection strategy:

  1. 宏觀應力與工法優化 (Macroscopic Stress & Method Optimization): 全面推動 3D/5D 大曲率冷作彎管取代對銲彎頭，輔以「三合一工法」穩定材料特性。 (Comprehensively promote 3D/5D large-curvature cold bends over butt-welded elbows, supplemented by the “Three-in-One Method” to stabilize material properties.)
  2. 微觀表面工程防護 (Microscopic Surface Engineering): 噴塗 Stellite 6 塗層並搭配雷射表面織構化（LST）預處理。 (Apply Stellite 6 coatings paired with Laser Surface Texturing (LST) pre-treatment.)
  3. 二次系統水化學精準調控 (Secondary System Water Chemistry Control): 全面導入 AVT(O) 或 OT，並注入 ETA 等中和胺。 (Fully adopt AVT(O) or OT and inject neutralizing amines like ETA.)
  4. 預測性維護 (Predictive Maintenance): 運用 EPRI CHECWORKS 系統實現動態壁厚預測。 (Utilize the EPRI CHECWORKS system to achieve dynamic wall thickness prediction.) 唯有深度跨領域整合，方能徹底截斷連鎖失效反應，保障CCPP高能管線的長期經濟壽命。 Only through deep cross-disciplinary integration can the chain reaction of failure be thoroughly severed, ensuring the long-term economic lifespan of CCPP high-energy piping.

參考文獻

  1. CCPP 系統中濕蒸氣之沖蝕行為預測與管件防護優化研究(Research, https://yz-pipe-bending.com.tw/ccpp-%E7%B3%BB%E7%B5%B1%E4%B8%AD%E6%BF%95%E8%92%B8%E6%B0%A3%E4%B9%8B%E6%B2%96%E8%9D%95%E8%A1%8C%E7%82%BA%E9%A0%90%E6%B8%AC%E8%88%87%E7%AE%A1%E4%BB%B6%E9%98%B2%E8%AD%B7%E5%84%AA%E5%8C%96%E7%A0%94/
  2. https://yz-pipe-bending.com.tw/%E8%A4%87%E5%BE%AA%E7%92%B8%E7%81%AB%E5%8A%9B%E7%99%BC%E9%9B%BB%E5%BB%A0%E9%AB%98%E6%BA%AB%E9%AB%98%E5%A3%93%E4%B8%BB%E8%92%B8%E6%B0%A3%E7%AE%A1%E7%B7%9A%E5%9C%A8%E9%A0%BB%E7%B9%81%E8%B5%B7%E5%81%9C/
  3. erosion-corrosion in wet steam and single phase lines in … – OSTI, https://www.osti.gov/etdeweb/servlets/purl/411309
  4. Mechanical Properties of P91 Steel (X10CrMoVNb9-1) during, https://www.mdpi.com/1996-1944/17/17/4398
  5. 複循環火力發電廠高溫高壓主蒸氣管線在頻繁起停運轉下的劣化機制, https://yz-pipe-bending.com.tw/%E8%A4%87%E5%BE%AA%E7%92%B0%E7%81%AB%E5%8A%9B%E7%99%BC%E9%9B%BB%E5%BB%A0%E9%AB%98%E6%BA%AB%E9%AB%98%E5%A3%93%E4%B8%BB%E8%92%B8%E6%B0%A3%E7%AE%A1%E7%B7%9A%E5%9C%A8%E9%A0%BB%E7%B9%81%E8%B5%B7%E5%81%9C/
  6. Type IV Cracking of Weldments in Enhanced Ferritic Steels – TWI, https://www.twi-global.com/technical-knowledge/published-papers/review-of-type-iv-cracking-of-weldments-in-9-12cr-creep-strength-enhanced-ferritic-steels/
  7. Water Droplet Erosion of Wind Turbine Blades – PMC – NIH, https://pmc.ncbi.nlm.nih.gov/articles/PMC6982018/
  8. (PDF) Assessment of a Wind Turbine Blade Erosion Lifetime, https://www.researchgate.net/publication/352795212_Assessment_of_a_Wind_Turbine_Blade_Erosion_Lifetime_Prediction_Model_with_Industrial_Protection_Materials_and_Testing_Methods
  9. (PDF) The Springer Model for Lifetime Prediction of Wind Turbine, https://www.researchgate.net/publication/358549957_The_Springer_Model_for_Lifetime_Prediction_of_Wind_Turbine_Blade_Leading_Edge_Protection_Systems_A_Review_and_Sensitivity_Study
  10. Wind turbine blade coating leading edge rain erosion model, https://www.researchgate.net/publication/325858475_Wind_turbine_blade_coating_leading_edge_rain_erosion_model_Development_and_validation
  11. Power Plant Water Chemistry | Corrosion, Scaling & Fouling Control, https://www.mt.com/us/en/home/library/know-how/process-analytics/power-plant-water-chemistry.html
  12. https://www.mdpi.com/2075-4701/13/4/806
  13. The importance of industrial water and steam treatment, Part 4, https://www.watertechonline.com/process-water/article/14301738/the-importance-of-industrial-water-and-steam-treatment-part-4
  14. HRSG issues: Reemphasizing the importance of flow-accelerated, https://www.power-eng.com/operations-maintenance/hrsg-issues-reemphasizing-the-importance-of-fac-corrosion-control-part-3/
  15. HRSG assessments identify trends in cycle chemistry, thermal, https://www.ccj-online.com/special-report-hrsg-assessments-identify-trends-in-cycle-chemistry-thermal-transient-performance/
  16. Influence of Ethanol Amine Injection on Flow Accelerated Corrosion, https://www.researchgate.net/publication/390833496_Influence_of_Ethanol_Amine_Injection_on_Flow_Accelerated_Corrosion_of_PWR_Secondary_System
  17. Reason Analysis and Control Strategy on Operation Corrosion in, https://www.researchgate.net/publication/333572431_Reason_Analysis_and_Control_Strategy_on_Operation_Corrosion_in_Direct_Air-cooled_Condensers_ACC
  18. Leakage Analysis of Steam Condensate Pipe Elbow – ResearchGate, https://www.researchgate.net/publication/370114710_Leakage_Analysis_of_Steam_Condensate_Pipe_Elbow
  19. (PDF) Enhanced oxidation of the 9%Cr steel P91 in water vapour, https://www.researchgate.net/publication/223331091_Enhanced_oxidation_of_the_9Cr_steel_P91_in_water_vapour_containing_environments
  20. Erosion-Corrosion of Alloys in Power Plant Heat Exchangers at, https://www.researchgate.net/publication/250343059_Erosion-Corrosion_of_Alloys_in_Power_Plant_Heat_Exchangers_at_Elevated_Temperatures
  21. (PDF) Influence of PWHT Parameters on the Mechanical Properties, https://www.researchgate.net/publication/361165117_Influence_of_PWHT_Parameters_on_the_Mechanical_Properties_and_Microstructural_Behavior_of_Multi-Pass_GTAW_Joints_of_P92_Steel
  22. The Effect of Electrolytic Hydrogenation on Mechanical Properties of, https://www.mdpi.com/1996-1944/13/16/3653
  23. Dissimilar Metal Welding — P91/P22 to Austenitic Stainless Steel, https://www.weldfabworld.com/welding-p91-to-p22-to-austenitic-stainless-steel/
  24. Numerical investigation and dimensionless erosion laws of solid, https://www.researchgate.net/publication/359593682_Numerical_investigation_and_dimensionless_erosion_laws_of_solid_particle_erosion_in_plugged_tees
  25. erosion-corrosion in oil and gas industry: a review – ResearchGate, https://www.researchgate.net/publication/264160200_EROSION-CORROSION_IN_OIL_AND_GAS_INDUSTRY_A_REVIEW
  26. Power Piping ASME Code for Pressure Piping, B31 – Academia.edu, https://www.academia.edu/32405461/Power_Piping_ASME_Code_for_Pressure_Piping_B31
  27. ANSI/ASME B31.1, “Power Piping” American National Standard, https://www.nrc.gov/docs/ML0314/ML031470592.pdf
  28. ASME-B31.1.pdf – Future Energy Steel, https://energy-steel.com/wp-content/uploads/2025/03/ASME-B31.1.pdf
  29. 基於ASME B31J 規範2″ XXS P91 高壓蒸汽管線5D 冷作彎管應力, https://yz-pipe-bending.com.tw/%E5%9F%BA%E6%96%BC-asme-b31j-%E8%A6%8F%E7%AF%84-2-xxs-p91-%E9%AB%98%E5%A3%93%E8%92%B8%E6%B1%BD%E7%AE%A1%E7%B7%9A-5d-%E5%86%B7%E4%BD%9C%E5%BD%8E%E7%AE%A1%E6%87%89%E5%8A%9B%E5%BC%B7%E5%BA%A6%E5%9B%A0/
  30. 基於ASME B31J 規範之P91/P92 高強度合金冷作彎管工法應力解析與, https://yz-pipe-bending.com.tw/%E5%9F%BA%E6%96%BC-asme-b31j-%E8%A6%8F%E7%AF%84%E4%B9%8B-p91-p92-%E9%AB%98%E5%BC%B7%E5%BA%A6%E5%90%88%E9%87%91%E5%86%B7%E4%BD%9C%E5%BD%8E%E7%AE%A1%E5%B7%A5%E6%B3%95%E6%87%89%E5%8A%9B%E8%A7%A3%E6%9E%90/
  31. https://yz-pipe-bending.com.tw/%E5%9F%BA%E6%96%BC-asme-b31j-%E8%A6%8F%E7%AF%84%E4%B9%8B-p91-p92-%E9%AB%98%E5%BC%B7%E5%BA%A6%E5%90%88%E9%87%91%E5%86%B7%E4%BD%9C%E5%BD%8E%E7%AE%A1%E5%B7%A5%E6%B3%95%E6%87%89%E5%8A%9B%EA%A7%A3%E6%9E%90/
  32. 複循環電廠高壓蒸汽管線洩水坡度設計與管件工法比較：斜切對銲, https://yz-pipe-bending.com.tw/%E8%A4%87%E5%BE%AA%E7%92%B0%E9%9B%BB%E5%BB%A0%E9%AB%98%E5%A3%93%E8%92%B8%E6%B1%BD%E7%AE%A1%E7%B7%9A%E6%B4%A9%E6%B0%B4%E5%9D%A1%E5%BA%A6%E8%A8%AD%E8%A8%88%E8%88%87%E7%AE%A1%E4%BB%B6%E5%B7%A5%E6%B3%95/
  33. 複循環電廠高能管線「彎管工法」整合研究：聲學共振抑制, https://yz-pipe-bending.com.tw/%E8%A4%87%E5%BE%AA%E7%92%B0%E9%9B%BB%E5%BB%A0%E9%AB%98%E8%83%BD%E7%AE%A1%E7%B7%9A%E3%80%8C%E5%BD%8E%E7%AE%A1%E5%B7%A5%E6%B3%95%E3%80%8D%E6%95%B4%E5%90%88%E7%A0%94%E7%A9%B6%EF%BC%9A%E8%81%B2%E5%AD%B8/
  34. TURKEYTRIB18 Oral Presentations Word | PDF | Lubricant | Friction, https://www.scribd.com/document/446850614/TURKEYTRIB18-Oral-Presentations-word-doc-docx
  35. Metals, Volume 10, Issue 9 (September 2020) – 164 articles, https://www.mdpi.com/2075-4701/10/9
  36. Stellite 21 coatings on AISI 410 martensitic stainless steel by gas, https://www.researchgate.net/publication/233567590_Stellite_21_coatings_on_AISI_410_martensitic_stainless_steel_by_gas_tungsten_arc_welding
  37. Comparison of Stellite coatings on low carbon steel produced by, https://www.researchgate.net/publication/332963880_Comparison_of_Stellite_coatings_on_low_carbon_steel_produced_by_CGS_and_HVOF_spraying
  38. Wear Mechanisms of Cold-Sprayed Stellite-6 During Reciprocated, https://www.researchgate.net/publication/373188082_Wear_Mechanisms_of_Cold-Sprayed_Stellite-6_During_Reciprocated_Dry_Sliding_Under_Different_Sliding_Speeds
  39. (PDF) Wear and Corrosion Properties of Stellite-6 Coating, https://www.researchgate.net/publication/340489797_Wear_and_Corrosion_Properties_of_Stellite-6_Coating_Fabricated_by_HVOF_on_Nickel-Aluminium_Bronze_Substrate
  40. Effect of Nitrogen Ion Implantation on the Cavitation Erosion … – PMC, https://pmc.ncbi.nlm.nih.gov/articles/PMC8124858/
  41. ERCoCr-E Filler Wire Supplier India | Stellite 21 Cobalt Wire CO21, https://www.nicorexalloys.com/ercocr-e-cobalt-alloy-co21-filler-wire-supplier/
  42. The International Association for the Properties of Water and Steam, https://competitivepower.us/pub/pdfs/volatile-treatment-review-2015.pdf
  43. https://www.ccj-online.com/combined-cycle-journal-issue-51/water-treatment-protect-equipment-against-corrosion-with-neutralizing-amines-filming-products/
  44. FossilPlantHigh-EnergyPipingDamage EPRI PDF – Scribd, https://www.scribd.com/document/395820927/FossilPlantHigh-EnergyPipingDamage-EPRI-pdf
  45. EPRI Guide Lines FAC | PDF | Energy Technology | Chemistry – Scribd, https://www.scribd.com/document/353381861/EPRI-Guide-Lines-FAC
  46. Controlling Flow Accelerated Corrosion PDF | PDF | Solubility – Scribd, https://www.scribd.com/document/481853014/Controlling-Flow-Accelerated-Corrosion-pdf
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