Document 5kbm8KaK3QExoKGoVX1MYY488
FILE NAME: Oil Industry and American Petroleum Institute (API) DATE: 1947 July
DOC#: API086
DOCUMENT DESCRIPTION: Trade Journal Article - Estimating Mineral Wool Insulation
In T h is Issue
WhosEeDRITeOceRsIsAioLn--FOaRnEdWWARhDen.......... 91
FlexibBley PRl.anSs. MfocrBRFeIDrtEilizer Making., 92
Volume 54
Number 7
JULY 1947
S. D. K IR K PA T R IC K ................................Editor JAMES A. L E E .................................... ManagingEditor THEODORE R. O L IV E .......... Associate Editor HENRY M. B A T T E R S............................ MarketEditor LESTER B. P O P E ................................ AssistantEditor RICHARD W, P O R T E R ......... Assistant Editor EDMOND C. F E T T E R ...........Assistant Editor RICHARD F. W A R REN .........Assistant Editor
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75 Years of American Chemical Progress................................
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Vinyl Acetate Production............................
98
By L. WILSON GREENE
`
Limestone Used to Neutralize Acid Wastes............................
100
By A. L. REIDL
Estimating Mineral Wool Insulation Costs............................
102
By FREDERICK C. OTTO
Estimating Costs of Installations of Chemical Equipment. . .
106
By f . R, BEHRENS
Estimation of Instrument Costs..............................................
108
By DOUGLAS M. CONSIDINE
Credit Swiping Nurses Hidden Losses....................................
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Quarter Circle Rule for Latent Heats......................................
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A CHEMICAL ENGINEERING REPORT
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: I
Estimating Mineral W ool Insulation
F R E D E R I C K C. O T T O
Supervisory Design Engineer, E. R. Squibb & Sons, New Brunswick, N. J.
INSULATION ESTIMATING IS NOT WELL ADAPTED TO SHORT-CUT CAL CULATIONS. THIS ARTICLE PERMITS M AKING DETAILED ESTIMATES
M ineral w ool in-
p
S S sulating materials,
E O Ug p p M E N T for hot piping and
C B fe.jU S
other equipment, has
a high rating from
thestandpoint of light weight and
high thermal efficiency. One of the
principal reasons why mineral wool in
sulations are not employed as much
as magnesia and asbestos insulation is
the fact that pipe coverers quite fre
quently complain of real or imagined
silicosis and dermatitis. It cannot be
denied that even when handling sam
ples of mineral wool products tiny
fibers quite often penetrate the skin of
the hands of the person handling such
samples. However, the use of a skin
protecting antiseptic ointment over
hands and arms, and other common
safety measures, will enable a me
chanic to install mineral wool pipe cov
ering, blankets, blocks and cement just
as quickly and efficiently as he would
install other standardized insulation
materials.
Mineral Wool Blankets
Mineral wool blankets are used for flat or slightly curved surfaces of larger types of heated industrial equipment.
The blankets consist of heat-resisting selected mineral wool, carefully felted and treated and secured between layers of metal fabrics of a large variety as listed in Table V. Blankets are widely used for heat exchangers, stills, tank cars, towers, boilers and breeches, kilns, ducts, tanks, vessels, ovens, washing machines, furnaces, vulcanizers and many other pieces of indus trial equipment. Owing to its low thermal conductivity, blanket insula tion is highly efficient; the efficiency can be increased by providing an air space within the insulation by using blankets with ribs turned out against the hot surface.
Estimators should be warned to in vestigate the type of blankets offered for specific insulation jobs. Not all
This is the second of a group of articles on the estimation of heat
insulation costs, prepared by Mr. Otto. The first, dealing with cork
insulation for cold lines and equipment, appeared in our May issue.
Remaining articles, which will be concerned with other higher tempera-
#
,
ture insulations, will appear frequently, the next in an early issue.
mineral wool products possess the same chemical and physical charac teristics. Mineral wool, also called slag wool, rock wool, etc., is made from a great variety of raw materials, among them lead slag, iron slag, lime stone, basaltic lavas, copper slag and slags from other metal production. Lead slag wool usually receives preference because of certain valuable characteristics not found in other mineral wools. A lead slag contain ing 30 to 50 percent calcium oxide or combined calcium and magnesium oxide will yield a good mineral wool. Slags of other compositions need added ingredients for decreasing brittleness of the fiber and attaining springiness and chemical resistance. W here large quantities are involved the estimator should secure copies of
the U. S. Government specifications|
for mineral wool blankets and should!
make certain that the offered mineral|
wool meets the tests for resistance tof
vibration, thickness of fibers, sho!|
content, water repellcncy, and alkaT
linity.
I
Because mineral wool blankets art
supplied in sizes of 2 x 4 ft. and 2x8
ft. the application can be done with ,
less labor in shorter time than would ,
be possible with most other insulation '
materials. The area which can be cov- ,
ered at one time is more than five j
times greater than standard sizes of 1
other prefabricated branded insub- F
tions. The thicknesses for best results
have been listed in Table III, from
which the estimator will note that
blankets are furnished in thicknesses ;
up to 8 in. Many operators, however,
Table I--Thermal Conductivity of Mineral Wool Insulation
Mean Temperature, Deg. F.
BO 100 ISO OO 250
-----------------------k Factor, B.tu./H r., Sq. Ft., De. F. per In.
/- ----------- ----- 6
Density, Lb. per Cu. Ft.--------------
8
10
12
0.220 0.270 0.320 0.380 0.430
0.232 0.273 0.318 0.387
0.400
0.215 0.255 0.297 0.342 0.383
0.262 0.290 0.320 0,355
0.385
Usual *
0.262 0.288 0.322 0.357 0.392
soo
0.480
0.442
0.426
0.418
0.428
8RO
0.B40
0.486
0.407
0.447
0.404
400
0.500
0.527
0.611
0.478
0.500
450
0,660
0.870
0.552
0.508
0.535
BOO
0.700
0.618
0.598
0.537
0.57
550
0.780
0.655
0.642
0.562
0.605
00
0.310
0.697
0.682
0.602
0.642
000
0.600
0.742
0.725
0.037
0.677
700
0.910
0.787
0.769
0.867
0.712
AW
0.750
00
1,1(10 1,200
0.810
o.ooo
1.000 1.100
* Noi*: The k factors listed uodor " Usual " represent maximum figures quoted by manufacturers of mineral wool insulations for their respective produota, i.e. blankets, pipe coverings and loose mineral wool
102
JU LY 1947 CHEMICAL ENGINEERING f
n
L-
L1S
>eat
ork sue.
icraisue.
ications should mineral
'ance to rs, shot ad alka-
lkcts are nd 2 x 8 one with m would nsulation n be covtlian five sizes of d insula,-st result* 111, from note that hitknesses , however,
Usual * 0.252 0.286 0.322 0.357 0.392 0.428 0.464 0.500 0.635 0.571 0.605 0.642 0.677 0.712 0.750
prefer to build heavy insulations up to the required thicknesses by using high temperature cement as a base
and blankets of 4-in. thickness to make up the total required thickness.
The list prices for blanket insula tion have been given in Table VI and the discounts are listed in Table XI. If the estimator has to calculate the job by material and labor, he should take the net cost of the blankets plus freight and hauling, the cost of the high temperature cement for under coat, if required, the cost of the ce ment finish coat, and finally the cost of the weatherproofing coat, if it is an outside job. In addition, he must estimate the cost of erection of the scaffolding, the tackwclding of angle
iron and cold rolled steel rings for supports of the blankets, and the ac tual labor cost for applying the blan kets as well as the coatings. How ever, all these costs for the complete application job have been estimated
Table 11--Thermal Conductivity of High Temperature Mineral W ool Blocks
Mean Temperature,
Dec. F.
200
400 600 800 1,000
Brand A
0.30 0.41 0.48 0.56 0.64
Brand B
0.41 0.45 0.60 0.75 0.90
1,200 1.4(H) I .coo
0.73
1.10
0.81
1,20
0.91
1.60
Tibie HI--Guide for Thickness* of Mineral Wool Blanket Insulation
Operatine Temperature,
Dec- I`
ion to 2i)o 201 to .'too 301 to 600 501 to 700 701 to 000
Thickness of Blanket,
In.
i U 2 2 A 3
Thickness t of Base Coiit, In.
901 to 1,100
3M
1,101 to 1,200
4
1,201 to 1,400
4
1,401 to 1,000
4
2
1,601 to 1,800
4
3
To the above thicknesses add a
coat of
Iptral woo) cement utul, for outeide installationa,
additional .l4-m. rout of wpalhcrwraling coin
ed on top of the cement finish,
t Consists of mineral wool nodules, asbestos fiber
jjd colloidal clay.
and arc listed in Table XII. The esti mator therefore need only add to gether the net price of the type of blanket chosen and the square-foot prices for application as listed in Table XII to arrive at the total cost of the installation.
Pipe Covering
Like the blanket type mineral wool insulation, mineral wool pipe covering is also made from high temperatureresisting and moisture-repellent, longfiber, specially selected mineral wool and the general specifications apply ing to blankets readily apply to pipe covering, since both are made from the same raw materials. Pipe cover ing is shipped flat and is fitted around the pipe for easy application. Mineral wool pipe covering actually is a small blanket, armored on the inside and the outside with expanded metal. The covering is held on the pipe by lacing the edges of the metal fabric together by means of No. 18 B.w.g. copper
Table
Tvpe No
1 2 3 4 6
V--Type Numbers and Identification of Mineral Woo! Blankets ^ _ am . 11_ _A_i A
One Side
W. M / W. M. W. M. ' W. M. W. M.
Other Bide
W. M. 8. L. E. M. H in. R. L. H in. R. L. (rib out*ide)
6
W. M.
H in. R. E.
-
W. M.
8
W. M.
M. L.
9
S. L.
8. L.
10
S. L.
E. M.
11
S. L.
A In. R. L.
12
8. L.
H In. R. L. (rib outoide)
13
8. L.
H in. R. L.
14
8. I..
in. R. L (rib outaide)
15
V. B.
F. 8.
10 H in. R. L. A in. R. L.
17
M. L.
M. L
18
M . L.
M In. R. L.
19
M. L.
H in, R. L. (rib outoide)
20
M. L.
% in. R. L.
21
M. L.
K in. R. !.. (rib outside)
22
E. M.
E. M.
23
A. P.
A. P.
* Key: W. M., 1 In. galv. wire mesh; B. L., tueco lath; F. S., Ho. 12 raeeh fly screen; R. L., rib lath; M. L., copper-bearing metal lath; E . M., expanded metal lath; A. P., asbestos paper.
Table IV--Guide for Thickness of Mineral W ool Pipe Covering*
Temperili ure. Den. F.
----- Pipe Diameter, Inches-------
2 to V A - - - ,-------- 4to4^----- ---. ^ -5 and u p-
u -I n s u l a t i o n T h i c k n e s s ,t In c h e s --
1
O
U
1
o
u
I
0
. , , 2 1 2 ................... . . . . 1
VA
1
1
154
1
I
VA
1
. - io 0 7 ................... . . . .
1
m
1
1
VA
1
1
VA
1
f. to 3 3 8 ................... . . . . 1
to 3 8 8 ................... . . . . 1
'j . i o SOO................... . . . .
1
1 'A
1
Vi
1
va
1
1
VA
1
1
VA
1
1 'A
2
1
1
1H
1
VA
2
1
VA
2
1
to . . ........... . . . .
m
2
1
m
2
1
2
2 A
IX
. ,0 TOO................... ____
VA
2
1
0
2 A
1A
2
2A
VA
' icSOO...................
0
2 'A
VA
2
ZA
VA
2 'A 3
2
U, 1,000.............. . . . . 2
2,4
va
2M
3
2
3
354
2X
0.810 0.900
1.000
1.100
manufacturan fgl oae mineral wa^.9
Sole: Mineral wool pii>e covering is not manufactured in thicknesses below 1 in. and not for pip -mg &diameter of less than 2 in. Key: " 1 " stands for inside piping, " 0 " etands for outside piping, **U Mstands for underground
CHEMICAL ENGINEERING JU L Y 1947
wire. The outside armor is usually full-fashioned copper-bearing expanded metal, whereas on the inside, against the hot surface, strips of the same material arc used. Mineral wool pipe covering is made in 2-ft. long sections; for small and medium diameter pipes one section goes around the pipe com pletely, whereas for large diameter pipes two or more segments may be required. These sections and seg ments are also available for circular equipment and pipes having diameters larger than 30 in. Upon request this blanket type pipe insulation may be furnished in rectangular sections of 12 or 24 in. width and 24 or 36 in. length, both sides reinforced with gal vanized wire netting of a wire thick ness of 0.035 in., and both layers of wire netting fastened to each other through the blanket itself by wire spaced not more than 8 in. centers.
It is a matter of personal prefer- --i ence whether a designer specifies min eral wool insulation or any of the other standard insulating materials for the average pipe covering job when no special difficulties arc to be ex- ,, pcctcd. However, for underground piping, for nested and bundled piping and certain other installations mineral wool pipe covering possesses definite advantages over other type of heat insulnnts.
In estimating pipe covering costs the engineer has to consider the cost of the material itself, the heat saving efficiency, the life of the insulation, and the cost of application. The heat saving efficiency is a result of the ther mal coefficient, and in the case of mineral wool insulation the k factor is closely related to the density of the material. Table I lists the thermal coefficients of mineral wool products of various densities and gives also the average k factors of several standard ized, branded mineral wool insula tions. U. S. Government specifica tions call for a maximum density of 12 lb. per cu. ft., including the weight of armor in the case of blankets and pipe covering. As long as the estima tor can get a guarantee of the density of the material to be offered he will be able, with the help of Table I, to determine the thermal conductivity and, therefore, the efficiency of the . insulation he proposes to use for a certain job.
The list prices for mineral wool pipe covering are listed in Table V II
and the discounts to the industrial buyer are given in Table XI. As in the case of mineral wool blankets the prices for mineral wool pipe cover ing are f.o.b. manufacturen' shipping points; the freight and hauling
io j
>JGINEERIS$g1
Table VI--List Prices for Mineral Woo! Blanket Insulation
Table V III--List Prices for Mineral Wool Hint
(Basis, dollars per square ft.)
Temperature Blocks
(Ba*is. dollars per sq. ft., f.o.b. shipping point*
2
9, 17 11, 5
13, 7
16
Thickness, List
Thickness,
List
Thickness.
3
10
12, 18
14
20
Inches
Price
Inches
Price
Inches
1
8
22
4, 19
6
21
15
23
M
*0.27
2 Vi
*0.68
1
0.40
0.45
0.55
0.60
0.70
0.75
0.60
0.65
H
0.27
24
0.75
Hi
0.45
0.63
0.60
0.65
0.75
0.83
0.65
0.70
1
0.30
2
0.83
1H
0.30
0.00
0.65
0.70
0.80
0.90
0.70
0.75
Hi
0.38
3
0.90
Hi
0.55
0.65
0.70
0.75
0.85
0.95
0.75
0.80
1A
0.45
3 fi
0.98
2
0.G0
0.70
0.75
0.80
0.90
1 . 00
0.80
0.85
Hi
0.53
3A
1.05
2M
0.70
0.80
0.85
0.90
1 00
1.10
2
0.60
4
1.20
3
.80
0.90
0.95
1.00
J.1 0
1.20
'! .t
3M
0.88
0.9S
1.03
1.08
1.18
1.28
4
0.115
1.05
1.10
1.15
1 25
1.35
Table IX--List Pric es for Mineral Wool Insulating Cement
4H
1.03
1.13
1.18
1.23
1.35
1.45
5
1.10
1.20
1.25
1.30
1.45
1.55
5 A
1.18
1.28
1.33
1.38
1.55
1.05
6
1.25
1.35
1.40
1.45
1.65
1.75
6A
1.35
1.43
1.48
1 .53
1.75
1.85
7
1.40
1.50
1.55
1.60
1.85
1,95
(Basis, dollars per
Quantity
C. L. lo b ....................... . . . . 40 Bags and over, but less
than C. L. L............. ___ 39 Bags and less.......... ___
50-lb. !mrt) National
Buyer *3.00
3.30 3.55
Averape Buyer S3.15
3.50 3.75
~>A
1 .48
i . r>8
1 .03
1.08
1 .95
2.05
8
1.55
1.05
1.05
1.75
2.05
2.15
* Note: Full freight allowance to bus-era de- f tination for C. L. L. For less than ear load lo'-1 t
Table VII--Lise Prices for Mineral Wool Pipe Covering
full freight allowance up to $1.25 per 100 It-
freight rate.
4
(Basis, dollurs per lineal foot)
Pipe Hi'*,*
Inches
---- 1
--
- Wiill Tluekne* of Covering. Inches---------- ---------- ....... ............
Hu
2
2 A
3
4
7 able X--List Prices * of Loi sr .uu t.rauul.H^
Mineral Wool
.
i2
0.70
0.90
1.30
1.65
2.20
3.10
(Basis, dollars per tonl
2 A
0.75
1.00
1.40
1.75
2.30
3.25
C. L. L, L. C. L.
3
0.85
1.10
1.50
1.85
2.45
3.40
Loose mineral wool.............. $52.00 $58.00
3 'A
0.95
1.20
1.60
1.05
2.00
3.55
Granulated mineral wool. . . 71.00
70.50
4
1.05
1.30
1.70
2.05
2.75
3.70
!
* Note: Full freight allowance up to $0.80
4M
1.15
1.40
1.85
2.20
2.90
3.85
100 lb. on C. L. L. and up to $1.25 per 100 lb. ot
5
1.25
1.50
2.00
2.35
3.05
4.00
L. C. L. The minimum car load quantity i*
6
1.35
1.65
2.15
2.50
3.30
4.20
24,000 ib.
7
1.50
1.80
2.30
2.70
3.55
4.50
8
1.65
1.95
2.50
2.95
3.80
4.80
with roofing felt or galvanized sheet
9
1.80
2.15
2.75
3.20
4.10
5.10
metal.
10
2.00
2.35
3.00
3.50
4.40
5.50
Tire cost of applied mineral woo!
12
2.20
2.70
3.30
3.80
4.80
6.00
pipe covering is the aggregate of the
14
2.50
3.00
3.00
4.20
5.30
6.50
pipe covering itself, freight, hauling,
1168 23..8100 33..6300 44..0400 45..6000 56..8300 77..6100 lacing wire, cement coat, roofing pa
20
3.40
3.90
4.80
5.50
6.90
8.20
per, scaffolding, and labor. In oidc;
24
4.00
4,60
6.60
6.40
7.90
9.50
to arrive at the total cost of mincr.d
30
3.00
5.00
6.80
7.80
* Sixes 2 to 12 in. are nominal; 14 in. and larger are O. D.
9.40
11.20
wool pipe covering the estimator
should determine the net delivered
cost of the pipe covering itself and
charges, therefore, must be added. The estimator will find that the list prices and discounts quoted by a num ber of manufacturers are identical. He, therefore, must make his choice on the differences in chemical and physical properties. Besides other re quirements mentioned before (see Blankets) the material to be selected by the estimator shall have not more
the installation of premolded sectional pipe covering, made from other stand ardized insulating materials, presents difficulties. The small rectangular mineral wool sections can easily be slipped around a pipe and the two ends are clamped together on the ac cessible side by means of hog rings or laced together with flexible wire. It is only necessary to have enough clear
should add the cost of installation as listed in Table XIII. It will be noted that only three thicknesses have been listed; application costs for other thicknesses should be approximated. The cost for application is based on $2 per hour for labor and cost prices for cement, canvas and roofing felt, wire, twine, etc., are those prevailing in June 1947.
than 20 percent by weight of shot, ance for the thickness of the blanket which are small glassy pellets and pipe covering itself. The thicknesses
Blocks and Boards
heads without recognizable insulating recommended for efficient heat saving Wherever flat surfaces of heated properties; the sulphur content must under various conditions have been equipment have to be insulated s.
be below 0.5 percent; the sodium ox listed in Table IV. If the installation against heat losses, the designing en ^
ide content must be below 0.25 per can he kept dry it is not necessary to ginccr will find that certain mineral
cent, and in the heat test the material cover the mineral wool, except when wool insulating blocks possess charac- ;
must be subjected for 6 hr. to 1,000 deg. F. without showing signs of fu sion, shrinkage or detrimental changes.
Mineral wool pipe covering is suit able for all heated pipes up to 1,000 deg. F. and is especially well adapted for buried pipes, for piping in trenches,
a neat appearance is required, in which case a coat of i-in. mineral wool cement or asbestos cement inav be applied. Or, instead of the cement finish, a layer of 45- or 65-lb. roofing felt may be installed. For greater heat savings economy, cither a cement coat
teristics which make the use of min- , cral wool desirable. These blocks arc : effective over the entire temperature S range up to 1,600 deg. F., and in the . case of products of a few manufac turers, up to 1,700 deg. F., in contrast ; with most other standardized insulat
channels, tunnels, and wherever pipes ing or roofing felt may be laid over the ing blocks which are made for either are so close to the ground, wall or pipe covering. For outdoor jobs it is high or normal temperatures, not j
ceiling (or to neighboring pipes) that reconunendcd to cover the insulation both. The k factors for these blocks
104
JULY W CHEMICAL ENGINEERING
hgh
-apt*
yer 15
SO 75
des ai lot 30 lb.
uiD tcd
C. L. *8.0 0 .'0.50
j.W ) | ?r
J Hi. on
Oily 13
sheet
i wool of the ading, ng pa i order nineral Innator ;livered elf and ition as c noted vc been . other dinated. iscd on st prices >ing felt, irevailing 1
Si
if heated insulated gning en- % n mineral ss charac*I e of min-1 blocks are: anpeiature mid in the i nimuifao s in contrast i cd insulat- ' for either tures, not? lese blocks \
arc lower than those listed in Table
I( as lim y be seen by comparing the
figures in this table with those in Table II. The density of these blocks
is usually 18 lb. per cu. ft., which is light in weight for high temperature insulating material.
As a rule these blocks are widely used for breechings, behind furnace refractories, for lehrs, ovens, boiler walls, annealing pits, hot air ducts, heat treating furnaces, kilns in glass and ceramic industries, chilling pits, pit covers, turbines, and tanks and towers in refineries. The thicknesses to be applied correspond with those given in Table III but no undercoat is required for higher temperatures. The maximum thickness of these blocks is 4 in.; a 6-in. thick insula tion, therefore, consists either of two bvers of 3 in. each, or one layer of 4 in and a second layer of 2-in. tliick,,css. For sizes and thicknesses of
high temperature mineral wool insu
lation blocks see Table XIV. For high temperature operations
tlicriiml expansion and contraction actors arc of prime importance. These blocks, when subjected to a tempera ture of 1,200 deg. F. in a muffle fur r,icc, showed only 0.03 percent diimkagc and at 1,740 deg. F. the shrinkage was only 0.84 percent. After bcina immersed in water for 72 hours the weight of sample pieces increased t,n1v 22 percent. W hen manufactured
TaM XI--Discounts From List Prices Minerni Wool Insulations
Product
-Discount, Percent-- . C. L. Lots L.C.L. Lots
.,,ml wool blanket. . . 65
63
vj.nrra! wool P'Pe cover`
*. t
.......... 05
G3
tem|enturc blocks
National buyers *
Zone 1................. 45
43
Zone 2................. 42
32
Zone 3.................. 43
33
V Aver* buyer *
Zone 1................. 41
37
Zone 2................. 35
24
Zone 3 ................. 30
25
jj,r n ii wool insulating
0
0
mineral wool..........
0
0
nnulated mineral wool.
0
0
Vote.* Zone 3 comprises certain counties in faiorado. Texas, California. Nevada, Oregon, bington, Wyoming: Zone 2 comprises most of
rtgt of the counties in Colorado, Nevada, Ore ** Texas, Washington; Zone 1 comprises prac-
. all the rest of United States.
by reputable companies, such blocks
are inert and chemically neutral, the pH value usually lying between 6.8 and 7.2. Their application is com monly done in the same manner as with magnesia blocks, asbestos blocks and other standardized insulating ma terials for the same purpose. How ever, high temperature mineral wool blocks may also be applied by means of hot asphalt; the blocks will not be affected when dipped in hot asphalt of 450 deg. F., picking up approxi mately 0.18 lb. asphalt per square foot of surface.
List prices are quoted in Table VIII and the respective discounts from the list prices are scheduled in Table XI. W hen estimating the cost of application the engineer has to consider the cost of the block itself plus freight and hauling charges in addition to the cost of the sundries used in the installation work and the labor cost. The sundries vary with the
type of finish desired. For inside in stallation a 4-in. coat of insulating cement, and a good paint coat, is usu
ally sufficient. Where damage to the insulation by labor, dripping water, or steam can be expected, 8-oz. can vas should be applied over the cement coat. For outside installations a layer of 65-lb. roofing felt or galvanized sheet metal should be applied. In all cases the cost of wire, bands, supports,
Table XII--Cost of Installing Mineral Wool Blankets *
Thickness, inches
i
p; IH IH 2
(Bas, dollar l>or aq. ft,)
-----------Installation Height----------- .
Below
15 to
Above
15 ft.
25 ft.
25 ft.
*0.75 0.80 0.85
0.00 0.05
*0.85
0.90 1.00
1.06 1.12
*0.92 0.98 1.09 1.14 1.19
m
1.00
J. 18
1.26
3
1.05
1.25
1.35
3'ii
l.m
1.30
1.40
4
1.15
1.35
1.46
4.4
1.25
1.45
1.69
5
1.30
1.60
1.70
5H
1.35
1.65
1.78
0
1.40
1.70
1.84
64
1.45
1.75
1.89
7
1.50
1.80
1.95
7 4
1.55
1.85
2.05
8
1.00
1.95
2.15
* Based on $2 per hour labor cost. Deduct 10 percent for inside jobs without weatherproofing.
Table X III--Cosi of Installing Mineral W ool Pipe Covering
flpeSUe, Isebea a
I 3 H
4
i
e
No Finish
SO.25 0.30
0.35 0.40 0.50 0.60 0.75
iM 10 cents per Un. ft, for
(Basis, dollars per Un. ft.)
-Thickness of Pipe Covering, 1 Id -
Roofing Felt
Sewed Canvas
Finish
Finish
SO.45 O.fco
0.63 0.60 0.70 0.80 0.95
SO.75
.
0.80
0.87
0.93
1.04
1.16
1.32
Cement Finish and Roofing Felt
SO.65 0.70 0.75 0.80 0.90 1.05 1.22
thickness and 15 cents per lin. ft. for 2-in. thickness.
.INHERING I CKf-MlCAL ENGINEERING JU L Y 1947
twirte, canvas, roofing felt, etc., has to he included in the calculation. The cost of labor depends on many fac tors, for instance the height of the equipment, the cost of erecting scaf folding, whether vertical or horizontal equipment has to be covered and. finally, what type of men will be of the job. For estimating purpose it will be close enough if the cost figures given in Table XII (applying to min eral wool blankets) are used for high temperature mineral wool insulation blocks and boards.
Insulating Cement
Mineral wool in the form of plastic cement is used as a base beneath other insulating materials, as a finish coat on top of other insulation, and for the covering of valves and fittings. It may also be used for the full covering of smaller pieces of equipment, especially when the surfaces are quite irregular. However, when larger pieces are to be insulated it is usually more econom-
Table XIV--Forms, Dimensions, Packaging and HcirruKes of Mineral Wool Insulations
B lankets
23 ty p es, a s liste d In T a b le V. T hicknesses from 1 to 8 in. Sizes 2 x 4 or 2 x 8 ft. Special sizes upon
m piest. T ncked In 200-lb. te s t c a rto n s o r c ra te s. Guide for selection of thicknesses, see
T ab le IIT. l ist prices, see Table VI. D iscounts from list prices, see Table XI. Cost of instalfation, see Table X II. T herm al conductivity, see T able I.
Pipe Covering
T hicknesses from 1 to 4 in. le n g th of sections, 2 ft. W idth of sections: to cover circum ference
of pipes 2 to 30 in. P acked in cartons or crates. Guide for selection of thicknesses, see
Table IV. L ist prices, see Table V II. Discounts, see Table XI. Cost of Installation, see Table X III. T h e rm a l c o n d u c tiv ity , see T a b le I.
H igh T em perature Block
T h ic k n e sse s from 1 to 4 In. S izes 6x18 in., 6 x 30 In., 12 X 18 in.,
12 x 3C in. S hipped in c a r to n s o f ap p ro x . 40 lb. a s
follow s: 2 4 - i n . th ic k blocks, 45 b o a rd fe e t p er
carton. 3 4 -In. th ic k blocks, 42 b o a rd fe e t p er
carton. A ll o th e r th ick n esses, 36 b o a rd fe e t p e r
carton. Guide for election of thicknesses, see
Table III. L is t prices, see T able VEIL Discounts, see Table XI. Cost of installation, see Table XII. T herm al conductivity, see T able II.
Plastic Ceascat
P a c k e d in b a g s of 50, 40, 35 lb. (m u ltiw a lt paper bags). "
T h ick n ess of In su latio n : % In. th ic k e r th an pipe covering.
I,Jt price, nee T ab le I3. D iscounts: none.
Loose and Granulated Fibers P a c k e d in m u ltiw a ll p a p e r b a g s of 35 an d
40 lb. L ist prices, see Table X. D iscounts: none.
105
ical to employ blankets, boards or blocks. The reason is the slowness in applying one layer after another of wet cement, the need of steam to dry out the layers, and the waiting period between the drying of each layer. This cement consists or mineral wool fiber, asbestos fiber and adhesive binders, thoroughly mixed, and is easily appliable with a trowel. Sodium chloride must be absent, sulphur content must be below 0.5 percent, shot content must be below 10 percent and the cement must not support corrosion. The thermal conductivity should be about 0.9 at a mean temperature of 200 deg. F. and 1.10 at a mean tem perature of 700 deg. F. For estimat ing purposes the engineer can take 50 sq. ft. of 1-in. thickness for 100 lb. of cement as a safe figure. Some brands of mineral wool cement exceed this coverage minimum; if the cover age is appreciably below 50 sq. ft. then the material does not possess
the same insulating value and must therefore be lower in price. The ad hesive property of mineral wool ce ment should be not less than 3 lb. per sq. inch. A shrinkage of 20 percent is
permissible, and the dried insulating cement should not weigh more than 30 lb. per cu. ft.
The list prices for this cement have been given in Table IX and as shown by Table XI there is no discount avail able, but freight allowance will be granted by the manufacturers.
Fiber and Granules
Mineral wool in loose and granu lated form has only restricted use in the chemical industry'. The insulating qualities of these two types are the same; they differ only in their physi cal shape. The loose wool is in long fiber form as itcomes from the cupola and in this form it is well suited for filling large areas such as on ovens or furnaces. The granulated form is the loose wool reduced to nodules varying in sizes from i in. to $ in.; this is used for filling more confined spaces where it is not easy to pack the bulk loose wool. In the industry we find both types principally used for furnace and boiler walls, hot water tanks, ex pansion joints, incinerator walls, glass annealing equipment, oven walls and,
in addition, as fill material around i
pipes in trenches and boxes.
j
A good mineral wool in loose and
granulated form will stand 1,350 deg. :
F. temperature without fusion; on ?
the other hand it must not absorb ,
moisture, and must retain its resili- ^
ence. A mineral wool which settles is [
of no value whatsoever. Mineral woo! 1
furnished for fill purposes usuallv !|.
weighs 8 lb. per cu. ft. and has J 1
thermal conductivity of 0.26 at 751
deg. F. mean temperature difference. ^
The k factors listed in Table I under 1
8 lb. density apply to the better grades [
of mineral wool. A material of this -
density will cover approximately 17 tn `
18 sq. ft. 3 in. thick per bag of 35 lb- ;
List prices for both types of miners': -
wool fill material have been given in
Table X and from Table XI it will be :
seen that no discount is applicable. ;
However, the manufacturers will allow r
certain freight rebates.
?
Cost of application cannot be given
because the entire cost is the wages :
for labor and since filling of open f
spaces with mineral wool can hardly ;
be called insulation work it is possible
to employ common labor.
;
Estimating Installations of Chemical Equipm ent
/. R. BEHRENS
Assistant Chief Mechanical Engineer, Merck & Co., Rahway, N. J.
/\v
T h is a r t ic l e is in
P ft) C E S S tended as a brief dis-
Q
P M E N T cussion of a few prac
r STS
tical methods of cost
estimating, including
the necessary philosophy pertinent to
good estimating. In large chemical
plants, the production and mainte
nance engineers have the advantage of
a special engineering division, where
facilities are available, which usually
includes mechanical and chemical en
gineers, estimators, project engineers,
structural and design engineers, drafts
men, etc. Their files are generally very
complete and contain manufacturers'
catalogs, cost standards, design stand
ards, and so on. This paper is not in
tended to interest such estimators.
The discussion, then, is directed to
ward the production chemist or plant
engineer in a small or medium sized
plant, who is called upon infrequently
by management to prepare an estimate.
Such a man has good cause to con
sider himself "on the spot." Few men
in this category have files of manufac
turer's catalogs and other information needed for proper selection of stand ard type equipment, and lack any facilities for estimating the cost of equipment requiring special design. If the estimator were given adequate time to consult with outside manufac turers, fabricators and engineers, he would be perfectly capable of arriving at a close and reasonable cost. How ever, this time is seldom to be had since management requires many weeks and sometimes months to formulate its future plans to the point of asking for an estimate. Yet, after the request for an estimate, time be comes of extreme importance. Al though management has many prob lems to settle oefore it is in a position to require an estimate, it is generally agreed that estimators are not given the time required to turn out a clear and eoneise estimate.
There are many methods used in estimating--the most amusing one is the well known "Guesstimate" or "Quickie." It is usually accomplished
by a telephone or verbal conversation j
in which a person requires a quick, ;
rough cost. This method is very vul- ,
nerable, as it results in snap judgment :
on the part of the estimator without
any thought given to the many de- ,
tails which may demand additional \
time and money at a later date. There
is justification for this tvpc of estimate .
if it is used to give management an |
indication of the financial scope of the ;
project. However, a formal estimate <
should be required for appropriation
purposes.
'
An estimate that is based on a simi
lar previous installation can be pro
duced satisfactorily with a minimum :
of thought and time, provided the esti- i
mator has a clear and concise picture ;
of what is required and has available ,
actual costs of previous installations.
Estimates that cover unfamiliar |
equipment, however, require the :
utmost in thought, vision, available .
specifications and a working knowl- f
edge of design. It is true that by con- 1
tacts with manufacturers, discussion
might bring forth many practical ideas
which could be included in the de- ;
sign and perhaps a verbal estimate
could be obtained. However, this pro- ,
cedure requires considerable time and
if the design is complicated, might still
require an outside consultant. Data
on hook-up items which are normally '
included in an estimate and include
pipe, fittings, valves and specialties i
in all materials of construction are 1
106
JULY 97 * CHEMICAL ENGINEERING