In stainless steel pharmaceutical production facilities - particularly in water and steam systems - reddish-brown to black deposits occasionally appear on internal walls. These discolorations are referred to as rouge or rouging. Purified Water (PW) and Water for Injection (WFI) systems, as well as steam systems, are typically affected. Rouging also occurs in systems made of high-quality materials such as 316L. The causes are oxidation processes or changes in the passive layer, in which iron components from the stainless steel react to form iron oxides/hydroxides and deposit on the surface.
在不銹鋼制藥生產設施中——尤其是在水和蒸汽系統(tǒng)中——內壁上有時會出現(xiàn)紅棕色至黑色的沉積物，這些變色現(xiàn)象被稱為“銹斑”或“紅銹”。純化水（PW）和注射用水（WFI）系統(tǒng)，以及蒸汽系統(tǒng)通常會受到影響。在使用高質量材料（如 316L）制成的系統(tǒng)中也會出現(xiàn)這種現(xiàn)象。氧化過程或鈍化層的變化是導致紅銹的原因，在此過程中，不銹鋼中的鐵成分會與空氣中的氧氣發(fā)生反應，形成鐵的氧化物/氫氧化物，并沉積在表面。
In practice, rouging typically manifests itself in water systems as a rub-off, reddish deposit. In hotter steam systems, however, dark to black, firmly adhering deposits are more commonly found (often described as 'blacking'). A common classification distinguishes between three classes: Class I as a wipeable, deposited corrosion deposit (without altering the underlying surface), Class II as an adherent corrosion product associated with insufficiently passivated surfaces, and Class III as a blue-black corrosion product (so-called magnetite), which typically forms in hot steam systems.
實際上，在水系統(tǒng)中，紅銹通常表現(xiàn)為一種擦掉后仍會殘留的、帶有紅色的沉積物。而在溫度較高的蒸汽系統(tǒng)中，更常見的則是深色至黑色、附著力很強的沉積物（通常被稱為“黑化”）。常見的分類將它們分為三類：第一類是可擦拭的沉積型腐蝕沉積物（不會改變底層表面），第二類是與未充分鈍化表面相關的附著型腐蝕產物，第三類是藍黑色的腐蝕產物（所謂的磁鐵礦），這種產物通常在高溫蒸汽系統(tǒng)中形成。
Why does rouging occur - and why, in particular, in hot systems?
為什么會出現(xiàn)紅銹現(xiàn)象？尤其是為什么會在高溫系統(tǒng)中出現(xiàn)這種情況呢？
The key factor is temperature: the hotter a system is operated or thermally sanitised, the more pronounced the rouging typically becomes. This is consistent with practical observations that rouging is virtually impossible to prevent entirely in systems stored at high temperatures or subjected to cyclic heating. At the same time, however, temperature control in water systems is a deliberate measure used to limit microbial growth. The reason for the increased formation of rouging at higher temperatures is the shift in the water equilibrium (autoprotolysis) towards the ionic side with H3O+and OH- ions at higher temperatures, whereby the hydronium ions represent the actual aggressive agent.
關鍵因素在于溫度：系統(tǒng)運行或進行熱消毒時的溫度越高，紅銹現(xiàn)象通常就越明顯。這與實際觀察結果相符，即在高溫環(huán)境中儲存或經歷周期性加熱的系統(tǒng)中，幾乎不可能完全避免紅銹現(xiàn)象的發(fā)生。然而，與此同時，對水系統(tǒng)的溫度控制是一種有意識的措施，用于限制微生物的生長。在較高溫度下紅銹現(xiàn)象增多的原因在于水的平衡（自動電離）向離子側發(fā)生了變化，在較高溫度下有H3O+和OH-離子存在，其中氫離子才是實際的侵蝕性物質。
In addition to temperature, the condition of the material plays a role. Technical articles indicate that rouging is linked to a destabilisation of the passive layer and that measures such as passivation and electropolishing can reduce the risk or delay its onset, without being able to prevent rouging entirely. Operating conditions such as flow/standstill and system operation can also influence the rate of rouging formation.
除了溫度因素外，材料的狀況也起著重要作用。技術文章指出，腐蝕現(xiàn)象與鈍化層的不穩(wěn)定有關，采取諸如鈍化和電拋光等措施可以降低風險或延緩其發(fā)生，但無法完全杜絕腐蝕現(xiàn)象的發(fā)生。諸如流動/靜止狀態(tài)以及系統(tǒng)運行等操作條件也會對腐蝕現(xiàn)象的形成速度產生影響。
Is rouging 'merely visual' - or a quality risk?
“紅銹現(xiàn)象僅僅是視覺上的問題嗎？還是存在質量風險？”
Rouging is often first noticed visually and does not necessarily result in abnormal routine test parameters such as conductivity. Rouging can become a concern if particles are introduced into the system and thus potentially into the product, or if even very small amounts of metal ions can affect a product's stability. For this reason, rouging is regularly inspected in practice, assessed as part of maintenance and addressed on a risk-based basis (e.g. with particular attention in biotechnological applications involving particle-sensitive steps).
紅銹通常首先會通過視覺表現(xiàn)出來，不一定會導致諸如電導率等常規(guī)測試參數(shù)出現(xiàn)異常。但如果系統(tǒng)中引入了顆粒，從而可能進入產品中，或者即使是很少量的金屬離子也能影響產品的穩(wěn)定性，那么紅銹就會成為一個需要關注的問題。因此，在實際操作中，定期檢查紅銹，作為維護的一部分進行評估，并根據(jù)風險原則進行處理（例如，在涉及對顆粒敏感步驟的生物技術應用中，應特別予以關注）。
Levers for action in practice - what can be influenced?
實踐中可采取的行動手段——哪些方面是可以影響的？
The greatest scope for influence remains the operating and sanitisation temperature. Several sources discuss that thermal sanitisation does not necessarily have to be 'historically' set at 80 °C, but that - depending on design, 'cold spots' and validated efficacy - lower temperature ranges may be common and sufficient (frequently cited: temperaturesabove 65 °C). However, a reduction in temperature must be carefully planned and validated so as not to "trade off" rouging against microbiological risks (e.g. biofilm in colder areas). Other influencing factors include the condition of the passive layer (passivation/electropolishing); furthermore, an overlay with nitrogen in tanks can exacerbate rouging. Ozonisation, on the other hand, can counteract rouging. The reason for this is the oxidising effect of the oxygen, which contributes to the formation and maintenance of the passive layer.
在操作和消毒溫度方面，其對結果的影響作用最大。多個來源指出，熱消毒并不一定必須“按照傳統(tǒng)方式”設定在80°C，但根據(jù)設計、冷點情況以及驗證的有效性，較低的溫度范圍可能是常見且足夠的（經常提及的溫度范圍：高于65°C）。然而，溫度的降低必須經過仔細規(guī)劃和驗證，以免“以犧牲表面粗糙度為代價來應對微生物風險”（例如在較冷區(qū)域出現(xiàn)的生物膜）。其他影響因素包括被動層的狀況（鈍化/電拋光）；此外，在儲罐中添加氮氣覆蓋可能會加劇表面粗糙度。臭氧處理則可以對抗表面粗糙度。其原因在于氧氣的氧化作用，這有助于形成和維持被動層。
In practice, rouging is removed using de-rouging processes; however, experience shows that it reoccurs after a certain period of time. What is crucial, therefore, is not so much a 'one-off' removal, but rather a lifecycle approach: monitoring, risk analysis, targeted measures and - if necessary - derouging plus restoration of a suitable surface condition (e.g. passivation). However, no chemical passivation processes are required to passivate stainless steel water distribution systems. If the stainless steel surfaces are clean, passivation is achieved within a few minutes due to the oxygen content of the water medium.
實際上，通過去污處理可以去除銹跡；但經驗表明，這種銹跡在一段時間后會再次出現(xiàn)。因此，關鍵不在于一次性徹底清除，而在于采用生命周期管理方法：監(jiān)測、風險分析、針對性措施，必要時進行去污并恢復適宜的表面狀態(tài)（例如鈍化）。不過，對于不銹鋼供水系統(tǒng)而言，并不需要使用化學鈍化工藝來實現(xiàn)鈍化效果。如果不銹鋼表面干凈，由于水介質中的氧氣含量，幾分鐘內就能實現(xiàn)鈍化。
Conclusion: Rouging cannot generally be completely prevented in hot pharmaceutical water and pure steam systems. The most effective lever is temperature (operation/sanitisation) - though this is always in tension with microbiological control. Passivation and electropolishing can reduce the risk, but they are no substitute for risk-based monitoring and a robust maintenance/sanitisation concept.
結論：在高溫制藥用水和純蒸汽系統(tǒng)中，紅銹現(xiàn)象通常無法完全杜絕。最有效的手段是控制溫度（操作/消毒）——盡管這始終與微生物控制存在矛盾。鈍化和電拋光可以降低風險，但它們并不能替代基于風險的監(jiān)測以及一套完善的維護/消毒方案。
京公網安備11010802046783號
