Tachanun is supplemented on Mondays and Thursdays by extended tachanunim starting "V'hu rachum". On those days, after tachanun is half-kadish (kadish l'ela, as some call it), a short paragraph that starts "Kel erech apayim", and the removal of the Torah scroll from where it's stored for reading.
I'm trying to determine whether "Kel erech apayim" is said on a Monday or Thursday on which tachanun is recited but the Torah isn't read from (because there's no Torah scroll, let's say, or because there's no one around who knows how to read it, or because there's no minyan, or some other reason). That, in fact, is my question, and you can stop reading now if you wish. The rest of this post illustrates whence my confusion has arisen.
Various sources seem to connect "Kel erech apayim" to tachanun, not to the Torah reading. The sidur of Bes Yaakov (Emden) clearly puts the paragraph in the section devoted to tachanun and not in the following section, devoted to the Torah reading. Shaare Efrayim, a book on the laws of the Torah reading, mentions (in chapter 10) various prayers said when the Torah scroll is taken out and put away, but does not mention "Kel erech apayim". And Taame Haminhagim mentions "Kel erech apayim" in paragraph 138, when discussing the late parts of shacharis, including tachanun, and not later, in the section about the Torah reading.
However, the ArtScroll sidurim and many other modern sidurim clearly put "Kel erech apayim" in the section devoted to the Torah reading. Not only that — the instructions in ArtScroll's English editions indicate that it's recited before the Torah is read, implying that it's not recited if the Torah isn't going to be read.
Is ArtScroll correct: do we recite "Kel erech apayim" only if the Torah is to be read? Does anyone (other than ArtScroll) say so?