June 5, 2015

Major Soryu hull life issue? - Maintenance/Emergency Welding in Japan only?

The following discussion of the Soryu hull, short operational life and welding in Japan only issues arises from "S"'s and my discussions on June 3-4, 2015 see Comments section for http://gentleseas.blogspot.com.au/2015/06/problems-with-submarine-purchase-from.html.

"S" explained on June 3, 2015, that one of the key technologies for the Soryu is the hull design and way of building it - which includes welds. "Submarine structure is made of series of cylindrical hulls reinforced by beams. Joints between hulls, connection of seam in hull, and connection between hull and beams are welded."

"In the case of [the] Collins submarine, GMA (Gas Metal Arc) welding was used for these hull buildings.[also called hull sections]"

"But it is not the case for Soryu submarine, GMA welding [is only?] used for hull-beam connection, [while] GTA (Gas Tungsten Arc) welding [is] used for hull-hull joint and seam connection in my opinion. [The] quality of GTA welding is superior to that of GMA welding, this technology is quite difficult to learn and it’s welding speed is very slow. There is no GTA welding technology in Australian submarine building sector. So hull building in Australia is rather risky and I can not recommend it in terms of Aussie submariners’ safety.

I then asked S "is Japan's hull making and welding practices designed for 20 years of submarine operational use, with problems developing if there are 10 more years of use?" [This is important because Japanese subs are typically operational for 20 years while Australian subs are ideally designed for 30 years service.] 

On June 4, 2015 S indicated:

"I think that [the Soryu] submarine may have material degradation issues for very long time use.

1. Fatigue which is structural damage from repeated loading: Submarine is exposed to very high pressure repeatedly. Sometimes tiny crack generates, propagates and finally leads fracture.

2. Corrosion which is damage caused by electrochemical reaction: Especially non-uniform corrosion like pitting is very dangerous. In the case of Soryu type subs, we’d better...pay special attention to the situation of interfaces [with the] anti-vibration rubber/hull.

3. We also must pay attention to stress corrosioncracking (SCC), the growth of crack formation under corrosive (sea water) and stress condition.

Prediction of these damages is difficult. But in the case of Soryu subs, JMSDF [the Japanese Navy] may accumulate important material data including degradation thanks to long operational experiences and consecutive building one of same type of submarine." [There is a life extension program for the Oyashio class (that precedes the Soryu class) but it is not known whether life extensions will be successful.] 

QUESTIONS

I would be most grateful for answers to:

Noting Submarine Matters records January 20, 2015 indicate the strength of steel used in the Soryu is "NS110" (equivalent to HY-156). This is much stronger and harder to weld than most submarines (including those from TKMS) which have a HY-80 strength rating. The safe depth most submarines can dive may be around 400 meters - but Soryus with their stronger steel may be able to dive to 600 meters.

1.  Is the high yield strength (equivalent to HY-156) of Soryu pressure hull steel the reason why GTA (Gas Tungsten Arc) welding is used?

2.  Or has GTA became the standard Japanese submarine welding method for other reasons?

3.  Does the deeper diving ability of the Soryu come at the expense of shorter 20 year old operating life?

4.  Put another why does the use of HY-156 (NS110) which allows deep diving put extra stress on the hull effectively shortening operational life to 20 years?

5.  If "[GTA] technology is quite difficult to learn and it’s welding speed is very slow. [And] There is no GTA welding technology in Australian submarine building sector. So hull building in Australia is rather risky and I can not recommend it in terms of Aussie submariners’ safety." Then

5(a)  How can deep maintenance, involving cutting and rewelding a Soryu hull, be done in Australia?

5(b)  If there is major battle damage to an Australian Soryu requiring cutting and rewelding the hull, how can that be done in Australia?

Pete

10 comments:

Anonymous said...

Just recycled from ELP:

In other words Japan is incapable to teach someone how to build submarines properly.

Sweden showed with Collins-class that it is not quite easy to export a working submarine.

Ask South Korea how it did worked.

Regards
MHalblaub

Anonymous said...

The Japanese armed forces replace its weapon systems quite frequently, it is not just 20 years for submarines, ditto for surface combatants, tanks, etc. I am speculating, but I suspect the 20 year life cycle may have to do with keeping the industrial base humming since Japan only builds weapons for its forces and cannot sell them like others can. Another reader commnted earlier on your site that the Japanese forces essentially stockpiled its "surplus" weapons when it receives newer ones so in time of war, it can call upon those stocks. Saying that 20 years is related to corrosion, fatigue stresses, etc.s is equally speculative.

Anonymous said...

I found japanese document about NS110 and GTA.
http://www.mod.go.jp/j/approach/hyouka/seisaku/results/13/jigo/honbun/04.pdf
Google translate worked.
It indicate that GTA is only way to keep toughness of NS110.
This document also indicate that soft joint enable to use GMA while keeping enough toughness.

Anonymous said...

Hi Pete

Answer Q1&2: Welding strength by GTA is higher than that of GMA.
Answer Q3&4: I am sorry I do not know.
Answer Q5(a)&(b): No

Continous engaging in welding task is one of most important requirements for welder’s qualification in USA, Japan and Eu. Aussie GTA welders for submarine can not satify this requirement or maintain his/her GTA skill, because Australia does not adopt continuous submarine building system. Welder can not maintain his skill by occasional or once a decade GTA welding. I think that realistic solution is combination of existing semi-automatic GMA welding and new welding friendly steel.

Regards
S

Peter Coates said...

Hi MHalblaub

Looks like Japan will need to share its expertise and train customers otherwise Australia will be the first and last customer.

See how much ASC now likes to CUT HULLS to increase maintenance efficiency http://www.asc.com.au/en/News-Media/Latest-News/ASC-innovates-in-submarine-maintenance/

Regards

Pete

Peter Coates said...

Hi Anonymous [of June 6, 2015 at 3:58 AM]

Japan may use subs for only 20 years due to keep "its industrial base humming since Japan only builds weapons for its forces" but Japan now needs to be flexible if it wants to build a successful export market. Otherwise Australia might be paying a full upfront price for Soryus that only last 20 years, that is only 2/3s of a German competitor's 30 year submarine lifetime.

If Japan "stockpiles" its weapon that is the Japanese Defence Forces own practice problem. It should not be a problem Australia buys into.

Anonymous where you say "Saying that 20 years is related to corrosion, fatigue stresses, etc.s is equally speculative." Well whats your knowledge of Japan's submarine industry. Are you from Australia or the US?

Regards

Pete

Peter Coates said...

Hi Anonymous [of June 6, 2015 at 5:01 AM]

Unfortunately Google translate for the document didn't work. Seems to be an Australian version of Word and/or PDF version incompatibility problem.

I would be grateful if you could identify which page and line(s) of http://www.mod.go.jp/j/approach/hyouka/seisaku/results/13/jigo/honbun/04.pdf reveal:

1. why "GTA is only way to keep toughness of NS110."

and that

2. "soft joint enable to use GMA while keeping enough toughness."

Regards

Pete

Peter Coates said...

Hi S

Thankyou for your answers to the Questions:

Q1. Is the high yield strength (equivalent to HY-156) of Soryu pressure hull steel the reason why GTA (Gas Tungsten Arc) welding is used?

Q2. Or has GTA became the standard Japanese submarine welding method for other reasons?

["Answer Q1&2: Welding strength by GTA is higher than that of GMA."]

Q3. Does the deeper diving ability of the Soryu come at the expense of shorter 20 year old operating life?

Q4. Put another why does the use of HY-156 (NS110) which allows deep diving put extra stress on the hull effectively shortening operational life to 20 years?

["Answer Q3&4: I am sorry I do not know."]

5. If "[GTA] technology is quite difficult to learn and it’s welding speed is very slow. [And] There is no GTA welding technology in Australian submarine building sector. So hull building in Australia is rather risky and I can not recommend it in terms of Aussie submariners’ safety." Then

5(a) How can deep maintenance, involving cutting and rewelding a Soryu hull, be done in Australia?

5(b) If there is major battle damage to an Australian Soryu requiring cutting and rewelding the hull, how can that be done in Australia?

["Answer Q5(a)&(b): No]

It may be a requirement of Australia buying the Soryu that MHI and/or KHI train Australian GTA welders and that the appopriate GTA equipment be supplied to Australia. Maintaining "his/her GTA skill" in South Australia or Victoria could be treated as an offset project which is often part of doing business in the weapon export trade.

I'm guessing one could not build or maintain Soryus with "semi-automatic GMA welding and new welding friendly steel" as this would completely alter the capabilities of what Australia is buying from Japan.

Thanks I'll summarise the issues in this article and thread and continue on issues raised next week.

Regards

Pete

Anonymous said...

page2 line13-17
1. ①鋼材の溶接手法(3種類)のうち「GTA(Gas Tungsten Arc)溶接法」のみが、従来潜水艦
の構造上必要と考えられていた所要のじん性を確保した上で溶接部の金属の耐力が母材と同等以上(等質溶接継手及び硬質溶接継
手)とする条件をみたすこと
2. ②GTA溶接より低コストである「GMA(Gas Metal Arc)溶接法」又は潜水艦の狭隘部の溶接に
不可欠な「SMA(Shielded Metal Arc)溶接法」のいずれかを適用しつつ、じん性を確保するためには、溶接部の金属の耐力が母
材より低くなる軟質溶接継手による溶接のみが可能であることが判明した。

Peter Coates said...

Hi Anonymous [of June 8, 2015 at 1:32 PM]

Thanks for locating page 2 lines 13-17 concerning GTA and GMA on Japanese language document http://www.mod.go.jp/j/approach/hyouka/seisaku/results/13/jigo/honbun/04.pdf [Basic research on welding of ultra-high-tensile steel used in submarine hulls].

Regards

Pete