Why the stainless steel ball of the seacock corroded again and again?

Have you ever feel helpless when some of the boat parts corroded faster than ever before ? Even you could not figure out what is exactly happened to your loved boat at last, the stainless steel parts, ball valves and the other parts which can be saw or not are corroded and replaced from time to time, but there is none of the solution solve these problem.

In fact, there are so many reasons for those which may caused because of the quality problem of the product itself or the parts in a corrosive environment for a long time. And today I will share with you a peculiar case which  we experienced with one of our business partner, and some interesting solution will be listed and shared with you at the end of this article.

Mr. Henry Lin,one of our distributors ,who is working with our products for many years. He is always express his satisfaction on our marine hardware and solutions we made anytime anywhere, that really help us to build a reliable business relationship with him. But, nothing is absolute. He was in our office for reporting a claim from his client last month. That would be the first time we felt his unhappy because of the products problem since we cooperated, even doubt that we bought the low quality raw material to process the seacock which the stainless steel ball corroded so fast that their client had to replaced it for 3 times in the passed 6 months. That also confused all of the rest of us in the office, but i didn`t deny the doubt, instead of explaining for our promised quality, i was asking him for more information about this case.

Henry said, Jack Lee is buying the parts from him for his owned yacht started from 2 years ago. In the beginning of this year, Jack asked the people to renew his yacht, including more new machines installed there. And something strange happened, the seacock at the same place corroded and replaced for 3 times in the passed 6 months. For the first time Jack raised the claim, Henry did not take it as a serious problem,just went and checked, and replaced a new seacock for Jack. But Henry realized that it could not be a easy question after 3 times of replacement in the passed 6 months, he was totally confused and turn to ask for a help from us.

The curiosity make us decide to check the problem. So we asked Mr. Kim go with us, who has been working on the boat building industry since the age of 20, he is kind of expert now after 23 years of rich experience on boats building. On the yacht, we were checking carefully one by one according to the guide by Jack, we noticed that the sea cock was corroded as they described before. Then Kim checked the system around and found that the abnormal voltage, at last, we confirm that the air condition near has a problem of electric leakage. It is my turn to be confused totally, it is really beyond my knowledge. Electric leakage? Any relationship between them? I asked.

Kim answered with a pale smile, we all know that the galvanic anode will be installed when we are building a yacht, for instance, zinc which protect the other metal parts from corrosion, it is because the metal activity of zinc is much more actively. Besides, the designer will design wiring for discharging the electric current to the zinc. So, apparently, the electric leakage accelerate of the corrosion process. But, another question, why only stainless ball corroded? Bronze as the main material of the sea cock, there are some patina adhered on the surface when the corrosion happened, it would not be possible the same corroded type as metal or stainless steel. Turn back to the seacock itself, there is an insulator which made with Polytetrafluoroethylene(PTFE for short) inside, PTFE cut off the transmission of the electric current between the stainless steel and bronze. Then, more and more electric current gathering inside the stainless ball and few out of there. It's also important to mention that if the ball valve use a brass / bronze ball inside, the valve will be got stuck because of the patina adhered on the surface, which will lead a serious safety problem, like boat sink. For sure, we had read a lot of that kinds of news, a seacock caused a boat sink.

All the questions got their answers suddenly at the time. But it seems that Jack is still feel down, as he had to remove the air condition for a new one which will spend a lot of time to go. I turn to Kim for a help, is there any contingency plan before that? Kim said, connect the wire with the stainless steel handle, lead the electric current to the galvanic anode, then done. It will not only solve the corrosion problem but also verify again whether it is because of the electric current or the other reason. Replace a new air condition or not can be decided after that.

Actually, the latest news from Jack had confirmed that Kim is right. It has been proven again and again that boat designing and building require so many technical supports. The tiny part as marine fitting will play an important role among them although they are not that larger size as engine. Target the real problem and solve it.

Origin written by Robin Zhang from New Xiang YI International Ltd.

www.nxymarine.com