Dockweiler is a leading international manufacturer of stainless steel tube systems. The core business is the development of installation solutions for handling fluid and gaseous media in the semiconductor, pharmaceutical, analytical and fine chemistry industries. The spectrum spans tubes, fittings, ball valves, hoses and components to complex make-to-order designs.
In our videos, we would like to answer important questions about stainless steel systems. How are specific products manufactured? How can material properties be influenced? Which standards apply?
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Contact: Dockweiler AG An der Autobahn 10/20 19306 Neustadt-Glewe , Germany
Great explanation. Thanks. I am a Master Trainer Welding Technology from Mumbai India. I am working as a freelance Professional Trainer and industry consultant.
you know about the tesla truck? you guys could make a corrosion test using stainless steels and using the ones from tesla truck too maybe to show corrosion even with rain... like make a time lapse or something could not be something related to your proposition but can be something to attract more eyeballs to your channel
Hello Dr. I 've heard that austenite micro structe should not be solidifeied to pure austenite to prevent hot cracks in welding and the last microstructure should be supported with some ferrite.
Hallo vladislavkuba5837, vielen Dank für deinen Kommentar. Grundsätzlich ist 1.4401 nicht für Salzwasser geeignet. Da sich eine klare Einschätzung jedoch nur geben lässt, wenn wir alle Bedingungen (Konzentration, Dauer, Temperatur etc.) kennen, wende dich gerne per E-Mail (sales@dockweiler.com), Telefon (+49 38757 580) oder über LinkedIn direkt an Dr. Torsten Köcher (www.linkedin.com/in/torsten-koecher/). 🙂
On your interesting video you show 4 example surfaces, all with the same Ra of 0,5 micron. The first is easy to clean, the last not. 1. What about the other two? 2. What roughness measurement system should be used instead of Ra to know which of these 4 types of surface (or other types) a tube internal diameter has? 3. Intuitively the third type in the graphic (flat plateaus and deep "V" valleys) looks least easy to clean - at least for very small residues - and maybe the second most attractive for biofilm.. do you have cleanability comparisons you can share? The available literature is very inconclusive - I think because most tests have been based purely on Ra and have not considered surface quality.
Thank you for a very interesting video. When discussing pickled tube you say that it is suitable for many, but not all, pharmaceutical applications. Can you please comment on the applications that this surface is less suitable for - and why?
There is dross formation when welding the high sulfur material because iron sulfide can form in the weld pool and finally solidify as a dross on the surface. How to overcome the dross formation with high sulfur material?
Hi, I would not consider the sulfur content a large source for dross or slag formation as the sulfur content is usually 0,005 - 0,017%. We consider the purity of either the heat itself or the purity of the surface much more important. The clean itself is unfortunately not cleanable anymore once it’s a tube. However, the surface is cleanable by pickling or electro polishing. At Dockweiler we perform welding tests for every heat before selling, so we know about weldability and slag formation. Regarding. For highly important parts we use ESR (electro slag remelted) or VIM VAR material. I hope that answers your question.
Guten Tag, wir haben heute in der Berufsschule behandelt, dass wenn der Delta - Ferrit Gehalt bei 0% ist, oder eben extrem gering. Diese Legierung dann zur Rissbildung neigt. Jetzt gibt es aber Hochlegierte Sorten wie den 1.4539 der gar kein Delta enthält. Trotzdem werden daraus Schmiedeblöcke hergesetllt und Frästeile angefertigt. Unser Ausbilder konnte uns aber nicht erklären wieso. Haben sie hier eine Erklärung? Selbst beim Schmieden würden Risse entstehen können. Aber dann könnte man daraus doch gar keine Schmiedeblöcke herstellen und schon gar nicht mit CNC bearbeiten.
Hallo, ich denk, dass es hier ein Verständnisproblem gibt. Mir ist nicht bewusst, dass Delta-Ferrit-arme Stähle zu Rissbildung neigen. Wir haben beim 1.4435 oder 1.4539 ja prinzipiell perfekt austenitische Strukturen vorliegen. Die sind ja faktisch gut dreh- und fräßbar. Delta-Ferrit sowie andere Phasen (z.B. Chi- und Laves-Phasen) weisen eine andere Struktur und andere physikalische Eigenschaften wie Härte und Sprödheit auf. Aus meiner Sicht treten die besagten Risse eher durch Anwesenheit als durch Abwesenheit Intermetallischer Phasen auf. Gruß Torsten
So when you suggest using nickel alloys, are you suggesting stainless alloys with a higher nickle content like 317, or nickle alloys like inconel? Im speaking In general, not specifically..
Hi, repeated solution annealing is of no particular use. Once you did a proper annealing and the austenitic structure is well defined repeated annealing would neither harmful nor beneficial. I hope that answers your question. Cheers Torsten
Dear Kundan, the parent pipe either sheet metal welded or seamless hollow from origin. Both pre-materials have undergone a slow cooling down phase in which the delta ferrite phase is dissolved in the material. Cool down time is app. 10 days. The weld seam cool down time is way too fast to dissolve the delta ferrite. Cool down time is some seconds Dissolve is certainly the wrong wording here. We are considering an equilibrium here depending on the temperature. The transition during or after welding is kinetically blocked as the metal is crystalized very fast and the atoms cannot move anymore. I hope that explains it. Best Regards
0:30 Warte mal Bro, ich esse gerade meinen Gurkensalat und hab mich verschluckt... Kriegen auch die Single Bubbies dieses Benefit genau so? Ist schon hart an Diskriminierung aufgrund des Geschlechts. Als Single Typ wenn ich sowas in der Firma mitkriege, erstmal mehr Geld fordern oder absolute Minimum leisten, könnte ich kotzen bei sowas.
Hi, Dr. Köcher. Yesterday i was discussing about the harmful level of HAZ depending on color. I have used your graphic showed in the video in order to define acceptable ranges for CPP. What I want to know is: when starts to lose the passive layer? As I understand Light raw yellow and pale yellow are not harmful zone, but what happened when the CPP decrease due to a brown color, is the passive layer missing? And what about the blue colors, in comparison with yellow seems like no problem occur. To explain better: SS 304L has a CPP about 500 mV, and after welding if HAZ appear the CPP could decrease to 270 mV and lose the passive layer, so for this value what would be the tint (yellow, brown or blue)? Could you be so kind to share with me the document that contain the graphic and their explanation? Saludos
Thank you Sir , we are using dockweiler pipes consistently in pharmaceutical industry and this small video has helped me to resolve my problem of black spots during welding.
Can we eliminate delta ferrite by heat treatment.. What is effect of delta ferrite on making Hollow pipes from solid bar by piercing process ? Final product is SS tubes for heat exchanger & pressure vessel application
Dear Narayan Rathod, Thanks for your interest in our videos and for your question. With regard to the upper mentioned process you will not create delta ferrrite. Even though you may find a value in the ferritoscopic testing, this result is caused by deformation Martensit which giving a result here as it’s ferromagnetic. If you need more information, feel free to contact us again.
@@deepakmandowara9833 Dear Deepak, as the measurement instrument is just detecting the potential for magnetization, there is no option to distinguish here. The only option is to be aware about the manufacturing process that were executed. However, a seamless tube which has not been annealed will have deformation martensit and will give a result on the instrument and a welded tube not annealed will give a signal as well whereas here you need to consider delta ferrite. Best Regards, Torsten
We are seeing point-like as well as grain boundary delta ferrite in 316L sintered at 1400 C. Is this (point-like) common or might be an error in EBSD phase map?
Hello, Dr. Köcher. Many thanks to explain as well this topic. I was investigating something around and I would like to contribute by mention that Acceptance Criteria is indicated in ASME BPE for product and non product contact surfaces. ISO 5817 also mention limits for imperfections for quality levels. An extract of "The Official Magazine of ISPE" by Ken Kimbrel, shows a tables where you can see weldings done by different oxigen level and its correspondance with piting corrosion resistance decrease, but also mention what level of resistance you could restore by post weld treatment like electrochemical cleaning and passivating. For the last, the Force Institute also provides a Chart with similar Heat Tint Levels and its correspondance with oxigen used in Argon or Formied gas. Saludos desde, México.
Здравствуйте, очень интересная информация в этом видео, но приходится догадываться до смысла, потому что не владею английским языком. Буду очень признателен, если сможете сделать субтитры с переводом на русский язык. Сотрудничаю с Вашим дилером в Москве АБС-СЕРВИС. Спасибо Вашу работу 🤝. Хорошего дня и настроения. По больше хороших клиентов.
Thank you! It's always great to hear when our videos are helpful. 👍😊 If you have any suggestions for topics, please feel free to send them to us. For specific topics, you can also always connect with Torsten on LinkedIn.
Very interesting. Thank you for that. I am looking into having Stainless steel components laser-welded, and the weld should be gas-tight. I've been told that a high sulphur content can lead to crack propagation. What are your thoughts on this?
Hi, the question is certainly what is “high sulphur”? We deal a lot with ASME BPE material, facing levels between 0,005 wt% and 0,017 wt%. We are using TIG. As far as I know laser welding is more narrow and deeper as the energy input is higher and the weld speed is higher too. Usually tube welded like that undergoes annealing. If there’s no annealing… might that be the reason? I’m not aware of reasons why sulphur could be the root course. Best Regards, Torsten
LDX 2101 is a Duplex steel so consists of ferritic and austenitic parts. It has a higher Manganese content compared to 316L which might lead to higher discoloration / manganese fumes. Due to the Nitrogen content it offers good corrosion properties as well. I would certainly consider it as an alternative for 304L but for hygienic purposes 316L is beneficial. However, all that depends on the application. Best Regards, Torsten 😊
The Coropad Testing indicates defects in the passive layer of a stainless steel. The passive layer in general is a view nano meters thick. As I believe the coating you are referring to is larger it’s questionable weather it works or not but I would give it a try.
