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actually last equation should return absoulte value: sC = ABS(sL - sH)

Ok, maybe I clear it up a little bit after Your input. So I have this model: For hoop stress: sHP = P*D/(2*t) For axial stress I need to take three load components: sLB .. bending stress (M/Z) sLP .. stress from internal pressure (SLP=Fa/A, Fa=P*Ai, A=pi*(D^2-d^2)/4) sLR .. stress...

Finally I got back to this topic .. As recommended I looked into ASME 31.8. Under section A842.2 "Strength considiration during operations" there is calculation for combined stress However, I can not get grip on those terms: Mo out-plane bending moment, in.-lb (N·m) Mi in-plane bending...

Thank You for valuable inputs. Corrosion on those sections is not deep as shown by last inline inspection (I'm not sure what is max depth right now, have no data on hand). Sections with higher corrosion will be cut out, and those with shallow corrosion will be only recoted to eliminate further...

Searching this forum shows quite many threads regarding pipe support. Most threads with specific answers are quite old (year <2005), and some general info is that there is no fixed rule or standard for pipe support distance. Has this changed in last few years? Is there now any...

I see that many posts regarding demagnetization topic is present in this forum. Let's try to be more practical. Let's say we have 20" pipe, and we measure 35 gauss on pipe end. Heat treatment is probably not suitable for demagnetization. Next option is demagnetization using welding cables. How...

That's the point of my post. I want second opinion or experience. Contractor is experienced (in few occasions they also subcontracted for TDW for hot tapping), and they sad that normal conditions are usually is around 20°C, but with preheating they do not expect additional problems. I just...

What are practical experiences with in service welding on high pressure gas pipeline (pressure containing metal sleeve)? Assuming that welding procedure is verified, preheat is controlled (up to 100°C), surrounding temperature is quite low (around -5°C), natural gas is flowing through 20" pipe...

Regarding buying low quality products: My intention is not to save money buying new low cost valves. However, we as company are obligated to use public tender, and cannot choose by name which valve we want to buy. Elimination level is technical specification, and second condition is lower...

What are practical experiences with refurbishing welded body ball valves for natural gas? We have some stock of leaking ball valves (PTFE seal, 12", 18", 20", Cooper Cameron, Argus, etc.). Experience with many of new valves (which often comes from China) are worse than 30 years old C.C. or...

Thank You all for answers, I will only update some facts. Pipeline is over 30 years old 18" gasline which transport dry and clean natural gas. Laminations are probably there from from start, but first ILI conducted by PII 7 years ago has not detected lamination (older generation of tools). Last...

As result of inline inspection, some of the anomalies are calsified as "possible lamination", and recomendation is to uncover pipeline and inspect anomaly. After that if it is really lamination which is not parallel to pipe surface, repair should be done. Question is, HOW TO INSPECT LAMINATION...

Polyken tapes are only for anticorrosion protection, and we use it also. Composite wraps (Black Diamond, ResQ, ClockSpring, PermaWrap, WrapMaster) are for reinforcement or repair of damaged pipe (corrosion damage, dent, gouge, etc.) We have used most of them, but Black Diamond and/or ResQ is...

As I can see from preview in PRCI, and from HSE guidlines, there is no mention of Black Diamond (new name Res-Q) composite wrap. This is carbon fiber composite wrap ofered by TDW, there for should be ok, but I can not find anyone with real expirience ..

What is Your expirience with composite wrap for onshore underground gas pipeline repairs? Until now we have used Clock Spring, some times WrapMaster (PermaWrap). I think this is fiber glass wrap's. Now we have some "Black Diamond" (Res-Q) which is carbon wrap, much more flexibile around...

I need more "rupture" effect than "leak". I will google for that also, but i hope that someone knows for some good source text already. This should not go into depth (not neccery), only to cover overview for "technical managment" people.

Is there any good site, magazine, book, powerpoint .. anything .. about pipeline burst monitoring (natural gas transmission) using pressure drop over time? We are using pneumatic devices which close pipeline when pressure drop is too high (change to electronic device is stared). I need to...

Is there any good tool for measuring DENTS on pipe (10"-28") at pipeline. Tool should be simple and portable. One point measuring is ok (like gauge), but recording profile of dent is also desirable (one axis or two)..

We need to buy compressor for natural gas. It must be an a explosion-proof edition, and it must be transportable by road. It will used to pump gas from one section of pipeline into next. Gas lines are in sizes 12", 20", 24" and 28". A length of sections is up to 15 km. Working pressures are up...

I have tried Panhandle B model in Excell: http://rapidshare.com/files/15502659/PanhandleB_-2.xls.html That is not really what I need. Last model from Sailoday is more like my solution. I will try with this one in new Excell worksheet. At this point, I have to admit that I do not understand...