06/25/2021 In Products Technical

So, the site plans say, "…connect to existing iron pipe." At present that we've dug down to it, I can't tell if it is grey iron or Ductile fe pipe. Are there ways to reliably distinguish betwixt the two without some physical testing on a sample? In this blog, we'll take a closer look at the characteristics and differences between the 2 types of pipe.

A Little Background About Cast Iron Pipe

Regarding atomic number 26 pipage, the word "cast" is most appropriately used as a verb, every bit in the act of making pipage itself. All iron pipes are cast. The earliest were cast in a formed sand pit, while modern atomic number 26 pipes are bandage in a centrifugal casting machine. Graphite, a critical component of iron pipes, evolved from its flaky composition in gray iron to the nodular graphite now within the ferritic construction of Ductile iron piping. This nodular graphite is the key to the resilient flexibility of Ductile atomic number 26 pipe.

Another major difference in the properties of these 2 iron alloys is that Ductile iron results from a much college level of estrus-treatment (annealing) to prepare its lasting metal chemistry and its superior strength, well across anything ever accomplished by gray atomic number 26. An evolutionary timeline from gray to Ductile iron pipe is worth a expect:

  • From the 1600s to near 1920 – Grayness iron pipes were "pit-cast," typically in sand molds.
  • The early 1920s - The centrifugal casting process of water-cooled molds spinning inside a machine to create a pipe wall emerges in earnest.
  • 1920's to Mid-1950s – The centrifugal casting of gray iron pipe dominates the industry—Pit-casting of fe pipes as a commercial model phased out in the late 1940s.
  • The mid-1950s – Arrival of the condom gasket as the primary sealing mechanism for watertight joints in iron pipe. To this day, the nigh pregnant advancement in pipeline joints in the history of utility piping.
  • The mid-1950s to mid-1960s – Innovative Ductile fe pipe is introduced and begins to appear sporadically. At this point, it might be considered an "experimental innovation."
  • The late 1960s to early 1970s – A confusing time for the iron pipe manufacture as both greyness iron and Ductile iron were ofttimes produced past the same foundries in the same machines, sometimes on the aforementioned days. This was the time that the textured peen blueprint was introduced in the spinning molds to utilise inoculant dust essential to the manufacturing of modern Ductile fe pipes.
  • The late-1970s – What was originally considered an experimental innovation, Ductile iron becomes the preferred pipe textile, virtually eliminating gray iron from active production.
  • From the early 1980s to the present – Gray atomic number 26 pressure pipe is no longer available as a stock detail.
  • NOTE: Grayness bandage fe soil pipe, generally used for gravity drainage of sanitary wastewater or other fluids from buildings, including the tallest skyscrapers, remains available and widely used around the earth.

Clues and Cues

Now that we've completed the IRON HISTORY lesson, let'south list some of the visual Cues and Clues that might allow you to "spot the difference" in such situations:

  • PEEN – All pit-cast and nearly centrifugally cast iron pipage had an intended smooth surface on the barrel exterior. All Ductile iron piping has the distinctive presence of a textured surface, known every bit the peen design. This blueprint is a raised and specific pebble-grain pattern on the barrel exterior.NOTE: Since gray iron and Ductile iron fittings are not centrifugally cast, they exercise Non have an exterior peen pattern.
  • Exterior Diameter – pit-cast grey iron pipe had varying outside diameters (OD), even forth the same piece of pipe. Pit and early on centrifugal-cast gray atomic number 26 piping often had shallow all the same noticeable voids and other surface irregularities resulting from the nature of the manufacturing process at the fourth dimension. Now, Ductile atomic number 26 has i nominal outside bore per size, which is consistent with other modern alternate materials. Why is it of import to know the inside and outside bore of your pipe? Find out in this Atomic number 26 Strong Blog by my colleague, Dustin Henderson.
  • MARKINGS – embossed or raised markings such equally the maker's name on a pipe's exterior barrel are a clear indicator that the piping is pit-cast grayness iron. Painted stenciling of product information on the barrel was common on late-term gray iron and Ductile iron piping until the early 2000s. Mod DI producers now use production stickers on each pipe for product information and quality verification.

  • STRUCTURE –greyness fe pipage typically had a box-like hub/joint connectedness rather than the airstream-style contoured bell of modern Ductile iron pipe.
  • JOINTING –if there are visible packing materials in the joint, such every bit oakum, a tarred heavy cobweb twine used to finalize the seal of the joint, it is gray-atomic number 26 piping. Ductile iron uses mod rubber gaskets to provide a lasting watertight seal for water or sewer systems.
  • Age – based on installation engagement - before 1965, information technology's likely gray fe. From 1975 and later, it's Ductile iron. For the decade of 1965-75, other clues are needed to reliably make up one's mind which material it is.
  • THE RING-A-DING DING – Some very experienced field veterans merits there is an audible difference in sound or pitch between the two materials when struck carefully with a metal hammer; with greyness atomic number 26 sounding more "ting-like" in response due to the lack of the softer annealing oxide layer nowadays on every Ductile iron pipe. This is much similar biting down on a money in the Old West to ensure it indeed was silver! However, this method is by and large unreliableon even a partially buried pipe as the soils effectually the pipe typically muffle any discernable sound difference.

A Niggling Bit Nearly Pipage Classes Through the Years

It's been said that the but certainty in life is change, and certainly, iron pipage wall classes are no stranger to this truth, every bit seen in the list below:

  • From the 1800s to the 1920s – Designated piping wall thickness classes of pit-cast gray iron pipes were largely restricted to A, B, C, or D. The further along in the alphabet, the thicker the wall.
  • 1908 to 1952 – Standardized pit and centrifugally-bandage thickness classes for gray iron pipe expanded to contain A - H, where again a Class F pipe would be significantly thicker than an A or B for a given nominal size pipe.
  • 1939 to 1967 – Standardized thickness classes for atomic number 26 pipe became a number-driven ranking from Class 1 to 8 for virtually diameters and up to Form 11 for others. The college the number, the thicker the pipe wall for whatever given diameter.
  • 1953 to 1982 – Standardized thickness classes specifically for grayness fe pipes centrifugally cast in metallic molds emerge with numbered designations from 21 to 28 beyond the available diameter range of 3-inch to 42-inch pipes.
  • 1965 – Ductile iron pipe is officially introduced in the marketplace with standardized thickness classes 1 through 6 beingness available.
  • 1976 – Equally more resilient walls of Ductile iron pipe became a true option, where a Class "0" became a potential thickness designation, a "5" was added in forepart to avoid impressions it might advise to stop-users. This resulted in the common cadre thickness classes of l through 56 Ductile iron pipes, at present referred to as "special thickness classes."
  • 1991 – Pressure class wall thicknesses for Ductile iron pipe were introduced to the marketplace to enhance the efficiency of pattern options and provide stronger competition against substitute materials. The tremendous strength of Ductile atomic number 26 allowed this transition, with the class of the pipe cogent its working pressure level rating. This force handles internal pressures capably, while also supporting external loads. There is some overlap between pressure classes and thickness classes, peculiarly in larger diameter pipes.

A Proud and Hearty Invitation

In doing the research for this commodity, it became apparent that while we know of countless older gray pipelines still in good service across the state, we take relatively few pictures of them or parts thereof that have been exhumed for whatsoever number of reasons. As sort of a "rolling republication" of this article, we hereby invite anyone and everyone to send us any picture of gray iron pipe y'all take in your archives. We volition proudly postal service them! Aid us advance the lasting truth of time-proven atomic number 26 pipe!

With these Pro Tips, you should be better able to distinguish between bandage iron pipe and Ductile fe pipe more readily in the field. Did we miss anything? If you lot know of whatever additional tricks or ways to non-destructively differentiate between the two, delight let united states of america know. Your Pictures and Pro Tips tin can exist emailed to Marketing@McWaneDuctile.com.

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Ken Rickvalsky, ENV SP, NACE CT

It'south been a fascinating three-decade run for me serving the water and sewer industry. Beginning with fourteen years at Griffin Pipe Products as their National Production Engineer, so developing that role further over the terminal 15 years with the McWane organisation, I have been blessed to meet the entirety of N America and much of Canada time and over again for as well many interesting scenarios to e'er list.

I've met and worked with countless wonderful people across all aspects of utility pattern, manufacture, structure, troubleshooting, and professional person development. Through the years many of them have become personal as well. I've loved every day of it, even the bad ones considering those are the ones where your graphic symbol, advice skills, and desire to productively assistance are non only required only tested. That'south what makes it fun. Stepping in when others are compelled to step dorsum.

Outside of work I savour quiet time with friends and family, sports of all kinds, and my greatest consignment ever ... being a Grandpa, courtesy of my son Kyle and his wonderful wife Erin.

ken.rickvalsky@mcwaneductile.com

https://www.linkedin.com/in/kenneth-rickvalsky-20265616b/