Lead caulked joints on C.I. pipe 3

[ODtape]

Are lead caulked joints as encountered in older cast iron water main lines (such as Class 250 or AWWA Class A pipe) considered to be restrained joints? Looking at the geometry of the joint, it looks like it should be self-restraining. It also looks like any movement caused by external force could unseat the joint. Can anyone recommend good reference material on this obsolete pipe joining system? My company has a private water distribution system for irrigation, parts of which have been in service for about 100 years. We have encountered C.I. elbows as large as 8" that have been in service for many decades with no thrust blocking.

 

[BigInch]

How far do you want to go back? I laid this fistulae

during the year now known as 79 A.D.

It has been hypothesized that Rome's dependence on lead water pipes lead to its decline. It has been suggested that the aristocracy died off from nothing more complicated than simple lead poisoning. This is not true. Since almost all of the lead absorbed by the human body is deposited in bones, investigators have studied the bones of ancient Romans. While some studies did indicate above normal concentrations of lead, it seems unlikely that water pipes were a contributing factor. Hodge (1981) has correctly pointed out that lead pipes would not have caused contamination for two reasons: (1) because the Roman water contained high concentrations of calcium which formed deposits inside the pipes, insulating the lead and (2) because lead will never greatly affect running water.

Now, in all seriousness, making new lead joints are now illegal in some states,

http://dnr.wi.gov/org/water/dwg/Forms/Lead.pdf#search="lead pipe joints"

In 1985 the EPA banned the use of lead in new public and private water systems and in plumbing repairs.

Modelling lead creep i nwater pipe joints,

http://www.fe-net.org/downloads/FEN...ch2004_DLE_Toft.pdf#search="lead pipe joints"

Axial Behavior Characteristics of Pipe Joints under static loading,

http://mceer.buffalo.edu/publications/resaccom/99-SP01/Ch6maragk.pdf#search="lead pipe joints"

Here is an AWWA doc you might be interested in springing for, Potential Techniques for the Assessment of Joints in Water Distribution Pipelines [Project #2689]

http://www.awwarf.org/research/TopicsAndProjects/execSum/2689.aspx

A history of pipe joining methods,

http://www.acipco.com/pipeprogress/fall-winter98/technical.html

and lastly, some tools you may be needing soon.

http://www.mephistotool.com/caulkingIrons.html#n

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[rconner]

Over the generations I believe there have been all manner/variations of "caulk joints", and for that matter and many different reasons (war years, shortage of lead, and probably other reasons?) all sorts/forms of caulking materials at times by various local practitioners/from myriad manufacturers. You are correct that the basic caulked joint (e.g. as depicted in the "Historical" section pg 12-2 of the American Pipe Manual at

http://www.acipco.com/adip/products/Sect12.pdf)

involving a socket groove, a spigot bead, and solid (probably most often in ages past lead) metal between is at least to some extent restrained thereby. I suspect in at least e.g. small diameter sizes, such well constructed restraint (at least when the spigot abutment/bead is present inside the joint) is probably even capable of withstanding substantial e.g. pressure thrusts. However, I'm not sure unless there are accurate records or investigations of exactly what is in the ground that one can depend 100% on this being the case at all specific locations. e.g. I think it is possible, perhaps for many reasons, that workers in ages past could have caulked at least a few joints that might not have had the spigot "bead" as depicted in the manufacturers' literature (e.g. using pipes "field cut" to a specific length e.g. to precisely position a valve,fitting, air release for some reason, or maybe even just to not waste a pipe with a damaged end etc. and thinking that axial "restraint" was not necessary then at that location). I think it may conceivably have been possible to develop a seal, at least with a straight joint assembled tightly together with sealing/isolating jute etc. packing and then the melted etc. metal though in those cases without the raised spigot "bead". Of course, there is also the possibility of some other sort of unrestrained sleeve or joints (e.g. Dresser etc. couplings or mechanical joint solid sleeves, that go quite a ways back themselves into decades of overlap with the use of caulked joint piping systems, installed in original construction or repair of damage etc.) In any case it sounds like your system may be close to eligibility for joining the more than six hundred other members in North America alone (if you are in this area) of the DIPRA "Century Club"!

 

[bimr]

Caulked joints that are presently used in plumbing are considered to be rigid nonpressure-type joints. These caulked joints are not considered to be restrained joints.

I understand that the older caulked joints of cast iron water mains were probably of the spigot and socket type, and caulked with lead, and that flanged joints were used for connecting to valves and other fittings. Judging from the number of leaks that have occurred, you would have to say that these joints were not restrained.

http://www.pirnie.com/index.php?option=com_content&task=view&id=287&Itemid=1014

 

[ODtape]

Thanks for the responses and the many useful links. The axial load tests were certainly interesting. Cast iron, a pipe material considered weak and brittle compared to ductile iron, took nearly twice as much compressive stress (without leakage) as ductile iron and showed no damage to the pipe material in the joint area. Meanwhile, in the same test, the ductile iron pipe spigot buckled and fractured. Also surprising to me is that the caulked joint telescoped more than .5” without leaking (!). It also mentions that tension testing was only done with joints that could resist tension. The fact that the caulked joint was not tested under tension suggests that the caulked joint cannot resist tension, or at least is not designed to resist tension. It would be nice if there were some sort of installation guide standard to reference. AWWA C108 is not available (not sure if it would have covered this anyway). Since ACIPCO is willing to provide information on their obsolete products, maybe I should ask them (?).

The cross sectional cut photo shown in the article on FE analysis of joint creep is also interesting. It seems to show that the lip on the spigot end was probably present to confine the oakum rope, and keeping it from migrating into the pipe when the it is being placed into the back of the joint. In my copy of Handbook of Water Control (F.E. Marimon, California Corrugated Culvert Company, 1944) it shows the same AWWA standard joint, as well as another variation that they call Super deLavaud centrifugally cast pipe. This version does not have the lip on the spigot end. Instead, the back .3-.5” of the bell-end socket necks down to create a more narrow gap. I would think that even without the lip, the pipe would still be unlikely to slip, due to the rough surface of the casting. Also, because of the v-shape of the bell-end groove, it would seem like any thrust force pulling on the pipe would just drive the lead seal even harder into the spigot surface.

According to ACIPCO, this joint was "obsolete" by the 1950’s, but I have a Mueller catalog from 1980 and they were still offering valves with caulk joints at that time. My company’s maintenance department was reportedly still making these types of joints in the 1970’s, and at least until a few years ago we still had some of the supplies and tools. I think our current operator may have discarded them, foolishly thinking he would not be needing them! (LOL) I know there are bell joint repair clamps available for leaks at these types of joints. I wonder if a leak could be repaired by just using an appropriate caulking iron to re-seat the lead seal? In the article linked by Bimr, I wonder exactly what the cause of failure was in these joints – corrosion? Excessive joint deflection from differential settlement? Here is study on this type of pipe in gas service:

http://129.105.121.69/publications/finno/deep_braced/deep_braced_case.html

They found that excessive leakage would occur after about .34 degrees of joint deflection.

My inquiry is not solely academic. For an upcoming project, I will be making a new connection to the end of a 8” C.I. service lateral installed sometime in the 30’s or 40’s. It presently has two 6” sprinkler valves on the end of it for watering the lawn. I’ll be removing the valves and connecting a new irrigation system, but need to verify that the lateral is truly restrained. Pouring a thrust block at the end of the lateral is not an option. I know from experience that the lateral will have either caulked joints or flanged joints (or both), but will not know for sure until we expose the entire length. If there are caulked joints that cannot be easily replaced, my preference is to leave them alone. If they are theoretically capable of safely restraining themselves (as they have been for decades) given working pressures, etc., I will leave the lateral as-is. If they are theoretically not capable of self-restraint, I will likely choose to cut out and replace portions of the lateral in order to install satisfactory inline thrust blocking, etc. I will consider purchasing the AWWA report as recommended by BigInch, in addition to seeking information from ACIPCO.

 

[BigInch]

I haven't read it, but the abstract sounded like it might be appropriate to your needs.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[rconner]

Both gray cast and ductile cast iron pipe, as well as joints thereof, have indeed generally been quite strong in direct compression (at least compared with many other contemporary engineering materials). In fact, I believe this compressive strength has even historically been taken advantage of in the form of structural columns, piles, and now even some contemporary “trenchless” systems developed for extremely high pushing or jacking pipe loads (e.g. see

http://www.acipco.com/adip/trenchless/).

Many restrained joint systems for gray cast iron as well as ductile iron pipe have historically also been very strong in direct tension. As far as the caulk joint probably most often used for underground gray cast iron water mains and as another poster has explained even long after the development of rubber-gasketed joints with generally more robust basic seals, while ACIPCO attempts to provide helpful information they alas cannot take credit for it as I believe the basic caulk joint was invented by a water company engineer in the London area more than a hundred years before now one hundred year-old ACIPCO was founded! Also, I suspect the joint members shown in the Historical section of the ACIPCO Pipe Manual I referred to also just basically conform to a decades old “American Water Works Association Standard” for 3”-48” pipes.
I have attempted to explain also in my prior post that it is extremely difficult for ACIPCO or anyone else to know exactly what you have in the ground. ACIPCO is one of several current producers of iron pipes, and I have even heard that prior to 1900 or five years before ACIPCO was founded, there were nearly a hundred other foundries producing gray cast iron pipes for a rapidly growing nation! The reason even quite strong gray cast iron material pipe is by many authorities more prone to overload failure than ductile iron pipe is that the gray cast iron material is roughly half as strong in tension, stronger in impact and bending strength, and ductile (as its name implies) unlike gray iron will by its nature yield or give some instead of break (of course within limits). For such reasons, I believe ACIPCO produced its last piece of gray cast iron pipe nearly thirty years ago and some time even prior to that would not produce any fabricated flange pipe without ductile iron flanges (I pre-date that just a little, so I have at least a little knowledge of this history and prior systems).
If you feel you need/must confirm the restraint ability of the old piping, would it be possible for you to somehow load or pressure/load test same e.g. at the terminus of the old piping, before you continue with the new (if a problem were to occur somewhere in the old piping, perhaps it would be good to find out about and fix this when the line was thus not in operation?) Also, at least based on what information has been provided thus far, I am having a little trouble visualizing why it might not even be possible to insulate the old piping some from thrust loads, e.g. with a “thrust collar” welded or clamped a short distance into the new piping and a transverse concrete thrust wall around same (that I would not think would normally need to be huge or hard to construct for 8” water piping loads). I hope this information is helpful.

 

[ODtape]

Thanks again for your responses. According to EBAA iron, prior to 1908 both OD and wall thickness of C.I. pipe were often specified by the customer (!). That year however, dimensional standards were created for letter designated pipe classes “A” through “H”. Presumably this was the AWWA C108 / ANSI A21.8 standard refered to in the ACIPCO literature. This AWWA standard is “withdrawn” and appears to no longer be available. I don’t know if it would have included any of the information I’m looking for.

I realize that neither ACIPCO nor anyone else has no way of knowing what we have in the ground. I don’t even know who manufactured the pipe. However, given the information that I do have, including the approximate time period of the installation, it appears to me to be a reasonable *assumption* that the installed pipe conforms to the AWWA C108 dimensions. My inquiry would be limited to the question of whether AWWA C108 caulk joint cast iron pipe when properly installed is self restraining, and if so, then under what pressure criteria. If I’m able to get an answer, I will post it in case anybody else is interested.

rconner, my description is difficult to visualize, but you are doing a good job. The thrust collar solution to isolate existing joints is basically the solution that I was alluding to in my previous post. The new piping immediately tees off at the end of the existing service lateral. Due to spatial constraints, I cannot install a thrust block there. That is why I would have to go back a distance into the existing lateral piping, cut it out and install new piping with a thrust collar and concrete TB. This is likely what I’ll end up doing. Another possible solution is to install a ductile iron wedge-style restraint on the existing cast iron pipe, and use that as a thurst collar. I don’t particularly care for that idea, as it’s viability depends greatly on the condition of the pipe (another unknown). Pressure testing is out of the question in this case. The isolation valve was either abandoned or never installed, so I have no way of isolating the lateral from the 2000’ long 14” C.I. mainline. Hopefully, when we saw-cut the pavement and expose the lateral, it will have only flange joints. That would simplify things a bit.

 

[rconner]

You may be interested in the more detailed history concerning these matters (developing I think at least from New England Water Works Association standards in 1902 or earlier)that is available on pages 1-2 on at

http://www.acipco.com/adip/products/Sect1.pdf.

As a matter of fact, I think most of this history actually appears in the foreword to many AWWA standards. While many standards from many organizations are listed, I'm not sure the specific ...A21.6 and ...A21.8 designations you refer were really there until much later than these earlier standards (in the '1950's or '1960's?)

 

[rconner]

Oops, just saw that the 22nd line in my 6 Oct 06 10:39 post above should read "...weaker in bending and impact strength". sorry

 

[ODtape]

Follow-up: While gathering field data for a current project, I recently encountered a pair of 4" 45-degree caulk-joint elbows installed at-grade without restraint. They are marked "ACIPCo 1937". I spoke with a technician at ACIPCO who informed me that they consider this type of joint to be seal-only; the joint itself would not offer any reliable form of restraint. He was surprised to learn that we have encountered so many examples of this type of installation that have not had failures. This particular pair of elbows mentioned above see a static pressure of 130 PSI and often see +/- 50 PSI surge pressures. Not only that, one of the fittings has a tree root growing under it that has obviously applied external force and movement to the joint! It has been in continuous service for about 70 years.

 

[rconner]

Given the further information and the many good references on this thread I am not surprisd this piping has worked well for 70 years (and even at quite high pressure and with the unblocked, at grade bends). I think many significant designers and installers of such piping at the time probably had an understanding of basically what restraint was available in the standard joints of the time, and additionally of issues such as when they cut a pipe end for example and made a joint or a cut-in with that end and "no bead", they were losing a component of that restraint and would need to externally block or tie any nearby fittings/valves etc. for any significant pressures. I suspect very few present technicians in any current pressure pipe company have poured/caulked nor tested standard caulk joint pipes, that I don't believe have been manufactured for many decades!

 

[dicksewerrat]

This type of pipe is the bulk of the water distribution systems in service today all around the world. Some repairs to these systems are still done with lead poured joints. This is a dying art in the pipe repair world. Call your local water system for more info.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[blueoak]

I also think people were a little more accepting of water lines out of service and helping with repairs. A town here finally replaced a "Michigan Pine" pipeline that had lead joints. Reading the old reports and stories it was expected that all travellers would delay their trips to fix the pipeline if any leaks were encountered. Also, reading the reports it seems that when designers messed up, fields crews just kept fixing it until it worked. Sorta different world.