PT encapsulation: greased sleeves? 2

[boffintech]

I have provided the backup info below and here's the question: On encapsulated PT sysyems are the transition components, the plastic translucent sleeves, at anchorages suppose to be filled with grease or not? The engineer at the PT company claims that filling the sleeves with grease is a "PTI certified plant recommendation" and not a "requirement". Is he pulling my leg?

ACI-318-05 18.16 Corrosion Protection for Unbonded Tendons

Code = 18.16.4 — Unbonded single strand tendons shall be protected against corrosion in accordance with ACI’s “Specification for Unbonded Single-Strand Tendons
(ACI 423.6).

Commentary = R18.16.4 — In the 1989 code, corrosion protection requirements for unbonded single strand tendons were added in accordance with the Post-Tensioning Institute’s “Specification for Unbonded Single Strand Tendons.” In the 2002 code, the reference changed to ACI-423.6.

ACI-318-05 3.8.4 — “Specification for Unbonded Single Strand
Tendons (ACI 423.6-01) and Commentary (423.6R-
01)” is declared to be part of this code as if fully set
forth herein.

So when I look in ACI-423.6-01 I read:

2.3.5 — Aggressive environments
The sheathing connection to sleeving at couplers and
to all stressing-end, intermediate, and fixed-end
anchorages shall be watertight and free of air spaces.

2.2.6.2 — Sleeves used to connect the sheathing to
the anchorage of encapsulated systems shall:

e) Be translucent or have another method of
verifying that the post-tensioning coating
material is free of voids; and

Commentary:
R2.2.6.2 — The requirements that prohibit voids may be
satisfied by filling the sleeves with post-tensioning coating. Transition components at anchorages and couplers should be designed to be void-free.

 

[ron9876]

It wouldn't make sense to grease the balance of the system and not grease an area near the end of the cables. It should be grease filled.

 

[boffintech]

The section of tendon inside the sleeve remains greased. However, the sleeve that covers the section of tendon with no sheathing at the anchor is simply a hollow tube filled with air. If it's filled with air how does that comply with...

ACI-423 2.3.5 — Aggressive environments
The sheathing connection to sleeving at couplers and
to all stressing-end, intermediate, and fixed-end
anchorages shall be watertight and FREE OF AIR SPACES.

I spoke with engineers at two different PT companies today and both said that the air space in the sleeve is only filled with grease if the SER specifies "void-less encapsulation".

My question is if the SER cites ACI-318 in the specs and 318 sets ACI-423 as the standard how does a sleeve filled with air equal "free of air spaces"? Isn't that tantamount to telling the SER who cites a code in the specs that he/she is required to repeat that code in the specs word-for-word and then say "yes, I really want that stuff."

 

[boffintech]

What started this inquiry was that I got a look at the submittal that the PT company sent in for its so-called encapsulated system. Combined and depicted on one page were TWO encapsulation systems: one with grease filled translucent sleeves and one with non-grease filled black sleeves. I called the PT company and asked why we were getting translucent sleeves that were not grease filled. Clearly the submittal shows that the system with translucent sleeves are grease filled thus meeting the requirements of ACI-318/423. The PT supplier (a PTI certified plant) confessed that they don't even own a machine that will fill the sleeves with grease. So it turns out that they can't even supply half of the components depicted in the submittal and ZERO effort was made to clarify this.

Am I on to something or just way off base?

 

[henri2]

I do not have ACI 423 so I cannot really help here. However, I do have a question for you. How much difference is there between provisions in ACI 423 compared with the PTI Specs for unbonded single strand tendons?

 

[boffintech]

How much difference is there between provisions in ACI 423 compared with the PTI Specs for unbonded single strand tendons?

Same as near as i can tell.

 

[henri2]

Thanks for the valuable information. Will certainly make comprehension easier. I'll try and purchase that document pretty soon.

Remember the discussion we had on a similar topic a while back?

http://www.eng-tips.com/viewthread.cfm?qid=143186

 

[AUCE98]

The industry is currently in a transition with the grease filled tubes. ACI-318 adopted the language from ACI 423, which is/was a recommendation at the time. Most consulting engineers are not aware of the requirement when they are specifying encapsulated systems. The PT supply companies are not supplying the grease filled tubes on a regular basis until ALL PT suppliers are held to the requirement. It really comes down to the $$. If company A has a price for an encapsulated system w/o grease filled tubes and company B has included the grease filled tubes, company B will typically have the higher price. Low man typically wins.

 

[boffintech]

A state of transition....huh. Well ACI-318 adopted ACI-423 all the way back in 2002. Seems like a long "transition" but as long as phony-balony submittals are doing the trick...

 

[boffintech]

BTW, talked to an engineer over at PTI late last week. He said that PTI stands by the code, ACI318 + ACI423.6: greased sleeves are required.

He also said that PTI was aware that producers are sending out phony-baloney submittals and shop drawings that depict greased sleeves but no greased sleeves are actually shipped to the job.

 

[boffintech]

New infor on the greased sleeve saga...

Just started a high-rise job and the parking deck has encapsulated PT. The owner apparently specifically requested encapsulated PT in the parking deck. So during the concrete pre-con meeting the special inspector has the absolute gaul to bring up the various requirements of ACI423.6 with regard to encapsulation. To our amazement the PT arrived at the job with the fixed end anchors having greased sleeves. Then the game of everyone pretending that no one knew how to field fill the intermediate and live end anchor sleeves ensued.

The logic of a) the spec requires it and b) the fixed end is greased so why wouldn't the other end be greased seemed not to matter.

But then to our further amazement a magical machine arrived at the job! It's nothing but a little pneumatic grease pump that sits atop a 5 gallon buck of PT grease with a grease gun with a long syringe: stick syringe up sleeve, pull trigger, slowly pull syringe out, place rubber grommet.

I took some pics of the machine so that at the next job when everyone goes into denial/obfuscation mode I can pull them out and thwart mediocrity.